Selective liquid-liquid extraction of oxidative desulfurization reaction products

ABSTRACT

The present invention provides selective extraction of sulfoxides, or sulfoxides in combination with sulfones, from hydrocarbon mixtures containing these compounds. A significant advantage of the invention is that oxidation products resulting from oxidative desulfurization of hydrocarbon feedstocks are selectively extracted with minimum co-extraction of non-oxidized products such as valuable hydrocarbon fuel components.

RELATED APPLICATIONS

This application is a Continuation of co-pending U.S. patent applicationSer. No. 13/627,606 filed Sep. 26, 2012, which claims the benefit ofU.S. Provisional Patent Application No. 61/539,734 filed Sep. 27, 2011,the disclosures of which are hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system and process for extraction ofsulfoxides or a combination of sulfoxides and sulfones, and moreparticularly to a selective liquid-liquid system and method for theextraction of oxidative desulfurization reaction products from ahydrocarbon mixture.

2. Description of Related Art

It is well known that certain sources of crude oil known as “sour” crudecontain significant amounts of sulfur. If chemically-combined sulfur,such as organosulfur compounds, is not removed from the resultanthydrocarbon products, including paraffins, olefins and aromatics,particularly gasoline, diesel or other fuels, its presence can causecorrosion of processing equipment and engine parts, as well as otherdeleterious effects, particularly when water is present. Further, thedischarge into the atmosphere of sulfur compounds during processing andend-use of the petroleum products derived from sour crude oil posesafety and environmental problems.

Conventional technologies such as hydrocracking and two-stagehydrotreating offer solutions to refiners for the production of cleantransportation fuels that, to some extent, meet certain regulatoryrequirements. These technologies are available and can be applied whennew production facilities are constructed. However, many existinghydroprocessing facilities, such as low pressure hydrotreaters, whichrepresent substantial prior capital investment, were constructed beforemore stringent sulfur specifications were enacted. It is very difficultto upgrade existing hydroprocessing systems because of the comparablymore severe operational requirements (i.e., higher temperature andpressure) to obtain clean fuel production. Available retrofittingoptions for refiners include elevating the hydrogen partial pressure byincreasing the recycle gas quality, utilizing catalyst compositionshaving greater activity, installing improved reactor components toenhance liquid-solid contact, increasing reactor volume, and improvingthe feedstock quality. However, all retrofitting alternatives arelimited by process economics and the basic existing hydrotreating systemupon which they improve.

Sulfur-containing compounds that are typically present in hydrocarbonfuels include aliphatic molecules such as sulfides, disulfides andmercaptans as well as aromatic molecules such as thiophene,benzothiophene, dibenzothiophene (DBT), and alkyl derivatives such as4,6-dimethyl-dibenzothiophene.

Among the sulfur-containing aromatic compounds, thiophenes andbenzothiophenes are relatively easy to hydrodesulfurize. The addition ofalkyl groups to the ring compounds increases the difficulty ofhydrodesulfurization. Dibenzothiophenes resulting from addition ofanother ring to the benzothiophene family are even more difficult todesulfurize, and the difficulty varies greatly according to their alkylsubstitution, with di-beta substitution being the most difficult todesulfurize, thus justifying their “refractory” appellation. These betasubstituents hinder exposure of the heteroatom to the active site on thecatalyst.

To keep pace with recent trends toward higher production of ultra-lowsulfur fuels, i.e., having sulfur levels at or below 15 parts permillion by weight (ppmw), refiners must choose among the processes orcrude oils that provide flexibility to ensure that future specificationsare met with minimum additional capital investment, in many instances byutilizing existing equipment.

The development of non-catalytic processes to carry out the finaldesulfurization of petroleum distillate feedstocks has been widelystudied. Certain conventional approaches are based on oxidation ofsulfur-containing compounds, e.g., as described in U.S. Pat. Nos.5,910,440, 5,824,207, 5,753,102, 3,341,448 and 2,749,284. Oxidation oforganosulfur compounds is a desirable process to minimize the sulfurcontent of hydrocarbon feeds, particularly to remove refractoryorganosulfur compounds such as dibenzothiophene and other aromaticorganosulfur compounds. During oxidation, the sulfur-containingcompounds are converted to their corresponding sulfoxides, having oneoxygen atom bonded to the sulfur heteroatom, and/or to sulfones, havingtwo oxygen atoms bonded to the sulfur heteroatom. Oxidation of certainsulfur-containing compounds increases their solubility in certainsolvents. The hydrocarbon stream containing soluble sulfoxides and/orsulfones are extracted from the hydrocarbon using a liquid-liquidextraction process.

Commonly owned Martinie et al. U.S. Patent Publication 2007/0051667, nowissued U.S. Pat. No. 7,744,749, discloses oxidative desulfurization ofdiesel fuel followed by liquid-liquid countercurrent extraction. Theoxidation uses an oxidant such as hydrogen peroxide combined with aceticacid. The oxidations products, mainly sulfones, are extracted with apolar solvent such as methanol, acetonitrile, DMSO, or DMF.

Schoonover U.S. Pat. No. 7,001,504 discloses a method for extractingorganosulfur compounds from hydrocarbons using ionic liquid. The organicsulfur is partially oxidized to sulfoxides and/or sulfones prior to orduring the extraction step. However, the selectivity of the ionicliquids to the sulfur-containing compounds is not discussed in thisreference. It is likely that non-treated organosulfur compounds, otheraromatics and other hydrocarbons are also co-extracted to a considerabledegree, thereby detrimentally impacting product yield.

Stanciulescu et al. U.S. Pat. No. 6,673,236 discloses catalyticoxidative desulfurization of hydrocarbon fuels followed by theextraction of oxidation products using a polar solvent. Ethanol was usedduring the catalytic oxidation step, and pure methanol was used as apolar solvent for removing the oxidized sulfurous compounds. However, itis known that the polar solvent methanol has a significant affinity fornon-treated sulfur compounds, aromatics and other hydrocarbons, thusreducing the overall product yield in a manner that may not becommercially acceptable.

While the processes described above can be effective to removesulfoxides and/or sulfones from a hydrocarbon mixture, problems remainrelated to co-extraction of other valuable hydrocarbon components, thusreducing the overall hydrocarbon product yield.

Therefore, it is an object of the present invention to provide a processfor selective removal of oxidized sulfur compounds from a hydrocarbonmixture that minimizes co-extraction of valuable hydrocarbon components.

SUMMARY OF THE INVENTION

The process described herein is directed to selective extraction ofsulfoxides, or sulfoxides in combination with sulfones, from hydrocarbonmixtures containing these compounds. A significant advantage of theprocess described herein is that oxidation products resulting fromoxidative desulfurization of hydrocarbon feedstocks are selectivelyextracted with minimum co-extraction of non-oxidized products such asvaluable hydrocarbon fuel components.

According to the process described herein, a selective solventformulation, which, as used herein refers to a solvent formulationhaving particular solubility to the target oxidation by-product, isbrought into contact with a hydrocarbon mixture during or afteroxidation reactions that produce sulfoxides and/or sulfones. In certainembodiments, the hydrocarbon mixture containing sulfoxides and/orsulfones is contacted with the selective solvent formulation under mildconditions, i.e., at a temperature in the range of from about 0° C. toabout 40° C., and a pressure in the range of from about 10 kPa to about205 kPa, in certain embodiments about 95 kPa to about 105 kPa, and infurther embodiments about 101 kPa.

The liquid-liquid extraction process can be carried out in a batchreactor, a continuous flow reactor, a tubular flow reactor, and/or in aliquid-liquid separator. An advantage of the process described hereincompared to prior art extraction processes relates to the use of aselective solvent formulation that minimizes co-extraction of valuablehydrocarbon compounds during the liquid-liquid extraction step.

Another advantage of the process described herein is facilitatingextraction of sulfoxides, and/or sulfoxides combined with sulfones,resulting from oxidation of hydrocarbon feeds by using the selectivesolvent formulation, thereby reducing the complexity and overall numberof extractive steps. In conventional approaches, pure solvent isrequired, and necessary steps include storage of large quantities ofhighly flammable solvent, recycling of large quantities of solvent withan evaporation unit and distillation unit with multiple stages ofcooling towers with associated tanks to segregate the sulfoxides andsulfones from the co-extraction of aromatics along with untreatedorganosulfur compounds. However, the process described herein isselective to extract the oxidized sulfur, and the solvent is recycledand separated from oxidized sulfur. In addition, polishing of oxidantmaterial can be accomplished by flashing water after extraction, whichcan eliminate acid, peroxide or solvent remaining in treated stream.Therefore, by employing the selective solvent formulations of theprocess described herein, the total sulfur will be reduced in a shortertime while minimizing the co-extraction of other valuable hydrocarbons.

A further advantage of certain embodiments of the process describedherein is the reduction of the oxygen required and a reduction in theoxidation reaction time by promoting formation of sulfoxides rather thanincreasing the oxidation to the subsequent step of sulfone formation.Sulfoxides can be formed using existing oxidation methods ofphoto-oxidation, photochemical oxidation, ozonation, ionic liquidoxidation, electro-chemical oxidation, bio-desulfurization, orcontacting with hydrogen peroxides, organic peracids,peroxomonophosphoric acid, nitrogen oxides and/or nitric acid. Ingeneral, sulfoxides are more easily extracted than sulfones. Sulfoxidesalone can be extracted with less solvent formulation. Under oxidationconditions using peroxides as the oxidation agent at mild operatingconditions such as temperatures of about 30° C. to about 40° C., bothsulfoxides and sulfones are formed.

With appropriate oxidation conditions and/or catalysts, sulfoxideproduction can be favored. Using certain solvents, the formulationconcentration can be increased to extract both sulfoxides and sulfoneswhile minimizing or eliminating co-extraction of untreated organosulfurcompounds.

As used herein, the term “sulfoxide products” refers to sulfoxidesresulting from oxidation of organosulfur compounds and “sulfoxidationproducts” refers to the combination of sulfoxides and sulfones resultingfrom oxidation of organosulfur compounds.

Also as used herein, the term “bulky sulfoxide products” refers tosulfoxides having more than 12 carbon atoms, thiophenes with more than 4carbon atoms, and sulfoxidation products of polyaromatic organosulfurcompounds such as benzothiophenes, napthothiophenes, dibenzothiophenes,naptho-benzo-thiophene and alkyl and dialkyl derivatives of any of theaforementioned aromatic organosulfur compounds.

In addition, as used herein, the term “bulky sulfoxidation products”refers to a combination of sulfoxides and sulfones having more than 12carbon atoms, thiophenes with more than 4 carbon atoms, andsulfoxidation products of polyaromatic organosulfur compounds such asbenzothiophenes, napthothiophenes, dibenzothiophenes,naptho-benzo-thiophene and alkyl and dialkyl derivatives of any of theaforementioned aromatic organosulfur compounds.

Further, as used herein, “non-bulky sulfoxide products” refers tonon-aromatic compounds including dimethyl sulfoxide, dibutyl sulfoxideand other sulfoxides having up to about 12 carbon atoms, or sulfoxideshaving a single ring structure, including thiophene sulfoxide and alkyland dialkyl derivatives of thiophene sulfoxide with alkyl groups, having1 to 4 carbon atoms.

Still further, as used herein, “non-bulky sulfoxidation products” refersto non-aromatic compounds including dimethyl sulfoxide, dimethylsulfone, dibutyl sulfoxide, dibutyl sulfone and other sulfoxides andsulfones having up to about 12 carbon atoms, or sulfoxides having asingle ring structure, including thiophene sulfoxide, thiophene sulfoneand alkyl and dialkyl derivatives of thiophene sulfoxide and thiophenesulfone with alkyl groups, having 1 to 4 carbon atoms.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing summary as well as the following detailed description willbe best understood when read in conjunction with the attached drawings.For the purpose of illustrating the invention, there are shown in thedrawings embodiments which are presently preferred. It should beunderstood, however, that the invention is not limited to the precisearrangements and apparatus shown. In the drawings the same numeral isused to refer to the same or similar elements, in which:

FIG. 1 is a schematic illustration of a system for sulfoxidation of ahydrocarbon stream and solvent extraction of the sulfoxidation productsaccording to one embodiment of the present invention;

FIG. 2 is a schematic illustration of a system for sulfoxidation of ahydrocarbon stream and solvent extraction of sulfoxidation productsaccording to another embodiment of the present invention;

FIGS. 3, 4 and 5 are plots of computational models of the activitycoefficient values for a range of concentrations of an acetone solventformulation for sulfoxidation products of DBT, thiophene and dibutylsulfide compounds respectively, relative to other components in ahydrocarbon mixture;

FIGS. 6, 7 and 8 are plots of computational models of the activitycoefficient values for a range of concentrations of a methanol solventformulation relative to sulfoxides of DBT, thiophene and dibutyl sulfidecompounds, respectively, relative to other components in a hydrocarbonmixture;

FIGS. 9, 10 and 11 are plots of computational models of the activitycoefficient values for a range of concentrations of an acetonitrilesolvent formulation for sulfoxidation products of DBT, thiophene anddibutyl sulfide compounds, respectively, relative to other components ina hydrocarbon mixture;

FIGS. 12, 13 and 14 are plots of computational models of the activitycoefficient values for a range of concentrations of an acetic acidsolvent formulation for sulfoxidation products of DBT, thiophene anddibutyl sulfide compounds, respectively, relative to other components ina hydrocarbon mixture;

FIGS. 15, 16 and 17 are plots of computational models of the activitycoefficient values for a range of concentrations of an acetic acidsolvent formulation for sulfoxidation products of thiophene,methylthiophene, and dimethylthiophene, respectively, relative to othercomponents in a hydrocarbon mixture;

FIGS. 18, 19 and 20 are plots of computational models of the activitycoefficient values for a range of concentrations of a formic acidsolvent formulation for sulfoxidation products of DBT, thiophene anddibutyl sulfide compounds, respectively, relative to other components ina hydrocarbon mixture;

FIGS. 21 and 22 are plots of computational models of the activitycoefficient values for a range of concentrations of anacetonitrile/formic acid aqueous solvent formulation for sulfoxidationproducts of thiophene and DBT, respectively, relative to othercomponents in a hydrocarbon mixture;

FIGS. 23 and 24 are plots of computational models of the activitycoefficient values for a range of concentrations of an aceticacid/acetone aqueous solvent formulation for sulfoxidation products ofthiophene and DBT, respectively, relative to other components in ahydrocarbon mixture; and

FIGS. 25 and 26 are plots of computational models of the activitycoefficient values for a range of concentrations of anacetonitrile/acetone aqueous solvent formulation for sulfoxidationproducts of thiophene and DBT, respectively, relative to othercomponents in a hydrocarbon mixture.

DETAILED DESCRIPTION OF THE INVENTION Process Configuration

Referring now to FIG. 1, a schematic flow diagram of for oxidation of ahydrocarbon stream and solvent extraction of oxidation products isshown. The concentration and type of sulfur compounds in the feedstreamare preferably determined prior to oxidation so as to optimize reactionand to employ suitable selective solvent formulations as describedherein. An integrated oxidation/extraction reactor zone 110, e.g., anagitator, a continuously stirred tank reactor, and/or other type ofmixing vessel, receives the sulfur-containing hydrocarbon feed via line112 and an oxidant via line 114. The oxidant can be acetic acid,hydrogen peroxide, or another suitable oxidant, or combination ofoxidants, as are known to those of ordinary skill in the art. The ratioof oxidant to the hydrocarbon feed can vary depending on the totalsulfur concentration and speciation. In certain embodiments, a suitableweight ratio of organic sulfur to oxidant is about 1:4, but it will beappreciated by one of ordinary skill in the art that the ratio can vary.In certain embodiments, the temperature and pressure conditions in theintegrated oxidation/extraction reactor zone 110 during the oxidationreactions are generally mild, e.g., a temperature in the range of fromabout 0° C. to about 40° C., in certain embodiments about 30° C. toabout 40° C., and a pressure in the range of from about 10 kPa to about205 kPa. The hydrocarbon and oxidant remain in contact for a period oftime sufficient to achieve a desired level of oxidation reactions, e.g.,between about 30 minutes and about 180 minutes. Compared to conventionaloxidation temperature of about 80° C. to 90° C., these mild conditionsresult in lower consumption of oxidant and desirably minimize theconversion of olefins, produce a greater proportion of sulfoxides, andminimize or eliminate the likelihood of polymerization. In contrast,higher oxidation temperatures result in a greater proportion of sulfonesas the oxidation product. Sulfoxide formation is generally preferredover sulfone formation, as less oxidant is consumed, and as describedherein, certain selective solvent formulations can be employed to targetsulfoxides while minimizing co-extraction of at least certain sulfonesand desired hydrocarbon products.

A predetermined quantity of selective solvent formulation is charged tothe integrated oxidation/extraction reactor zone 110. At least a portionof the solvent enters via a recycle line 116 from a solvent recoveryzone 124 once the system has achieved a steady-state operatingcondition. The selective solvent formulation extracts sulfoxides, or acombination of sulfoxides and sulfones, that have been formed during theoxidation of the sulfur-containing hydrocarbon material. The selectivesolvent formulation can be present in a ratio of solvent-to-hydrocarbonin an amount of about 1:2 to about 3:1 by weight, depending on thesulfur speciation of the hydrocarbon stream, the degree of oxidation,and whether the target oxidation products for extraction includeprimarily sulfoxides or a combination of sulfoxides and sulfones. Forextraction of non-bulky sulfoxide products and/or sulfoxidation products(i.e., combined sulfoxides and sulfones), a ratio toward the lower end,e.g., 1:1, is suitable. For extraction of bulky sulfoxide productsand/or sulfoxidation products, a ratio toward the higher end, e.g.,about 2:1 to about 3:1 is suitable.

Hydrocarbon mixtures including the oxidized or partially oxidizedhydrocarbon contents are contacted by intimate mixing with the selectivesolvent formulation for a period of time that is sufficient to extractthe sulfoxides, or combination of sulfoxides and sulfones, andsolubilize them in the selective solvent formulation, e.g., betweenabout 10 minutes and about 60 minutes. In certain embodiments, thetemperature and pressure conditions in the integratedoxidation/extraction reactor zone 110 during the extraction step, aregenerally mild, e.g., a temperature in the range of from about 0° C. toabout 40° C., in certain embodiments between about 15° C. and about 40°C., and a pressure in the range of from about 10 kPa to about 205 kPa,in certain embodiments about 101 kPa (about 1 atmosphere). In certainembodiments, a separate cooling step is not required between the stepsof oxidation and extraction.

After the mixing and extraction are completed, the mixture is allowed tosettle for a period of time sufficient to result in phase separationbetween the hydrocarbon phase and the solvent phase, e.g., between about60 minutes and about 180 minutes.

The solvent phase containing the selective solvent formulation andextracted sulfoxides, or combination of sulfoxides and sulfones, isdecanted via line 118 to the solvent recovery zone 124. The recoveryzone 124 can be an evaporation operation, in which the contents areheated to a temperature of about 110° C. to evaporate water and solventat atmospheric pressure for recovery via line 116 to the integratedoxidation/extraction reactor zone 110, and the oxidized organosulfurcompounds in liquid form are recovered and evacuated via line 126.Extracted sulfoxides and sulfones can be treated to cleave thesulfur-oxygen bonds by pyrolysis reactions to recover sulfur-freehydrocarbons (not shown).

A reduced sulfur-content hydrocarbon stream is passed via line 120 to anoptional polishing zone 130 from which a polished stream is dischargedvia line 132. The polishing zone 130 can be one or more suitablepolishing apparatus capable of removing impurities such as organic acidsthat can remain after solvent extraction. For instance, an aqueouspolishing unit can be used due to the ability to recycle the polishingwater stream. Another suitable type of polishing unit is a solidpolishing unit based on adsorption of acidic organic molecules that canbe carried over with the hydrocarbon stream. In addition, adsorbentmaterial in a solid polishing unit can adsorb any remaining sulfoxidesand/or sulfones in the hydrocarbon stream. The adsorbent material caninclude one or more of clay, alumina oxide, silica gel, molecularsieves, zeolite, a combination thereof, or any other adsorbent materialor combination of adsorbent materials known to one of ordinary skill inthe art. In additional alternative embodiments (not shown) thehydrocarbon phase transferred via line 120 from the integratedoxidation/extraction reactor zone 110 can be directly discharged andused as a feedstream for further refining operations, or collected as anend product.

Referring now to FIG. 2, a schematic flow diagram of a system 200 foroxidation of a hydrocarbon stream and solvent extraction of theoxidation products is shown. The hydrocarbon feed, oxidative materials,process conditions, and other parameters are similar to those of system100, with the exception that the oxidation reactions occur in a zoneseparate from the solvent extraction. An oxidation reaction zone 205receives a sulfur-containing hydrocarbon feed via line 212 and anoxidant via line 214. The oxidation reaction zone 205 is generally amixing device, such as an agitator or a continuously stirred tankreactor. In certain embodiments, the temperature and pressure conditionsin the oxidation reaction zone 205 are generally mild, e.g., atemperature in the range of from about 0° C. to about 40° C., in certainembodiments between about 30° C. and about 40° C., and a pressure in therange of from about 10 kPa to about 205 kPa. The hydrocarbon and oxidantremain in contact in the oxidation reaction zone 205 for a period oftime sufficient to achieve a predetermined level of oxidativedesulfurization, e.g., between about 30 minutes and about 180 minutes.

The hydrocarbon stream containing the oxidized products is passed vialine 207 to a solvent extraction zone 209. A quantity of selectivesolvent formulation is charged to the solvent extraction zone 209 viarecycle line 216 from a solvent recovery zone 224. The selective solventformulation extracts the sulfoxides, or combination of sulfoxides andsulfones, that are formed during the oxidation of the sulfur-containinghydrocarbon material. In certain embodiments, the temperature andpressure conditions in the solvent extraction zone 209 are generallymild, e.g., a temperature in the range of from about 0° C. to about 40°C., and a pressure in the range of from about 10 kPa to about 205 kPa.

The oxidized or partially oxidized hydrocarbon contents are contactedwith the selective solvent formulation by intimate mixing in the solventextraction zone 209 for a period of time sufficient to extract thesulfoxides, or combination of sulfoxides and sulfones, e.g., betweenabout 10 minutes and about 60 minutes. Mixing is discontinued and thecontents are allowed to settle for a period of time sufficient to allowphase separation of the hydrocarbon phase and the solvent phase, e.g.,between about 60 minutes and about 180 minutes.

The solvent phase containing the selective solvent formulation andextracted sulfoxides, or combination of sulfoxides and sulfones, isdecanted via line 218 to the solvent recovery zone 224, similar to thatdescribed with respect to system 100. A reduced sulfur-contenthydrocarbon stream is passed via line 220 to an optional polishing unit230 from which a polished stream is discharged via line 232. Inadditional alternative embodiments (not shown) the hydrocarbon phaseexiting via line 220 from the solvent extraction zone 209 can bedirectly discharged and used as a feedstream for further refiningoperations, or collected as an end product.

General

In contrast to known extraction processes, the process described hereinemploys selective solvent formulations that are less than 100% puresolvent. The solvent concentration is selected to target the sulfurspeciation of the hydrocarbon mixture that is subjected to the oxidationreaction(s). Therefore, extraction of the target sulfoxide orsulfoxidation products occurs selectively, with minimal co-extraction ofother hydrocarbon constituents such as dodecane (nC₁₂), toluene,naphthalene, thiophene, dibenzothiophene and dibutyl sulfides, whichwould otherwise result in an undesirable decrease in product yield.

In general, the selective solvent formulation is an aqueous solutionhaving a concentration range of about 2.5 weight % (W %) to about 70 W %polar organic solvent in water. The polar organic solvent can beacetone, methanol, acetonitrile, acetic acid or formic acid. Theparticular concentration within this broad range can be specified basedon the particular polar organic solvent employed, the sulfur speciationand whether the target oxidation product includes a full range ofmolecular weight sulfoxide products or combined sulfoxidation products,bulky sulfoxide products or sulfoxidation products, or non-bulkysulfoxide products or sulfoxidation products.

Combinations of two or more of the polar organic solvents in aqueoussolution can also be effective in extracting target oxidation products.For example, mixtures can include acetonitrile, formic acid and water;acetone, acetic acid and water; acetone, formic acid and water; andother mixtures comprising water and two or more polar solvents selectedfrom acetone, methanol, acetonitrile, acetic acid and formic acid.

For hydrocarbon mixtures having bulky sulfoxide products or bulkysulfoxidation products, the selective solvent formulation is providedwith a relatively higher concentration of polar organic solvent. Forinstance, the concentration of the aqueous polar organic solventsolution can be about 30 W % to about 70 W %.

The following descriptions provide the activity coefficients (γ) ofvarious solvent formulations relative to certain hydrocarbonconstituents including sulfoxidation products based uponcomputer-modeled simulations using COSMO-RS (COnductor-like ScreeningMOdel for Realistic Solvents) software commercially available fromScientific Computing & Modelling NV, Amsterdam, The Netherlands. As isknown to those of ordinary skill in the art, lower values of theactivity coefficient represent higher solubility of the particularconstituent in the solvent, while higher values of the activitycoefficient represent lower solubility of the particular constituent inthe solvent.

The modeled γ is based on calculations of sulfoxide and sulfonemolecules as solute to be extracted from the mixed hydrocarbon stream.The hydrocarbon stream of non-extracted hydrocarbons is defined as theraffinate. Reference to the values of γ set forth in the followingtables allows selection of solvents with minimum co-extraction of otherhydrocarbons.

It has been determined that γ values of 0 to about 16.5 correspond toextraction of acceptable levels of the oxidized molecules. However, γvalues of about 16.5 or greater indicate extraction rates that are notpractical for the oxidation products, but desirable for the non-targetedspecies, i.e., avoiding solubilization of the non-targeted hydrocarbonsand unconverted organosulfur compounds.

Furthermore, a relatively large difference between γ values of thetargeted oxidized sulfur compounds and the other non-targetedconstituents is preferable, as this large difference indicates minimalco-extraction of the raffinate components. In addition, a largedifference increases the selectivity of solvent formulation to extractthe targeted oxidized organic sulfur compounds. Therefore, in thepractice of the process described herein, the optimum formulation isbased on maximizing the difference in the respective γ values.

The value of the activity coefficient of the targeted compounds (γ_(T))is minimized while the value of the activity coefficient of thenon-targeted compounds (γ_(NT)) is maximized. In certain embodiments,the ratio γ_(T-DBT-Sulfoxide):γ_(NT-DBT) is at a maximum 1:5, whereinγ_(T-DBT-Sulfoxide) denotes the activity coefficient of targetedcompound dibenzothiophene sulfoxide and γ_(NT-DBT) denotes the activitycoefficient of non-targeted compound dibenzothiophene. However it hasbeen determined a desirable ratio γ_(T-DBT-Sulfoxide):γ_(NT-DBT) can beas low as 1:10, 1:20, 1:50, 1:100, 1:500 and, in certain embodiments, aslow as 1:1600.

Model Feed Information and Sulfur Speciation

The first model fuel (referred to herein as “model A” with correspondingnomenclature in the activity coefficient tables that follow, i.e.,tables 2A, 3A, 4A, 5A, 6A, 7A, 8A and 9A) used as the input to theCOSMO-RS software along with the various solvent formulations are basedon a straight run diesel sample containing various concentrations ofnon-sulfur alkane constituents from C₈ to C₂₅.

The second model fuel used (referred to herein as “model B” withcorresponding nomenclature in the activity coefficient tables thatfollow, i.e., tables 2B, 3B, 4B, 5B and 6B) as the input to the COSMO-RSsoftware along with the various solvent formulations are based on astraight run diesel sample containing the following non-sulfur alkaneconstituents: C₈ (0.4 W %), C₉ (1.3 W %), C₁₀ (3.1 W %), C₁₁ (6.1 W %),C₁₂ (8.4 W %), C₁₃ (9.9 W %), C₁₄ (11.2 W %), C₁₅ (11.7 W %), C₁₆ (11.7W %), C₁₇ (10.3 W %), C₁₈ (8.8 W %), C₁₉ (6.7 W %), C₂₀ (4.9 W %), C₂₁(2.9 W %), C₂₂ (1.6 W %), C₂₃ (0.8 W %), C₂₄ (0.3 W %), C₂₅ (0.1 W %).In addition, the diesel used for model B has an aromatic concentrationranging from 15 W % to 30 W %. The sulfur speciation of the diesel usedfor the below models is as follows:

TABLE 1 IUPAC name Concentration, ppm Benzo[b]thiophene  8 ± 15-methyl-1-benzo(b)thiophene 42 ± 8 4-methyl-1-benzo(b)thiophene  9 ± 22,6-dimethyl-1-benzo(b)thiophene  81 ± 152,4-dimethyl-1-benzo(b)thiophene 179 ± 322,3-dimethyl-1-benzo(b)thiophene 404 ± 732,3,4-trimethyl-1-benzo(b)thiophene 189 ± 342,5,6-trimethyl-1-benzo(b)thiophene  6 ± 1 dibenzothiophene 387 ± 704-methyldibenzothiophene  706 ± 127 2-methyldibenzothiophene and  587 ±106 3-methyldibenzothiophene 1-methyldibenzothiophene 380 ± 684-ethyldibenzothiophene 195 ± 35 4,6-dimethyldibenzothiophene 350 ± 632,4-dimethyldibenzothiophene 249 ± 45 2-ethyldibenzothiophene  69 ± 123,6-dimethyldibenzothiophene  771 ± 139 2,8-dimethyldibenzothiophene 338± 61 1,4-dimethyldibenzothiophene  615 ± 1111,3-dimethyldibenzothiophene 179 ± 32 1,2-dimethyldibenzothiophene  95 ±17 2,4,8-trimethyldibenzothiophene 335 ± 604-ethyl,6-methyldibenzothiophene 288 ± 52 4-propyldibenzothiophene  82 ±15 2-propyldibenzothiophene 256 ± 46 4-butyldibenzothiophene  62 ± 112,4,7-trimethyldibenzothiophene and  75 ± 132,3,8-trimethyldibenzothiophene 2-butyldibenzothiophene 111 ± 202-pentyldibenzothiophene  93 ± 17 1-phenyldibenzothiophene 11 ± 24-phenyldibenzothiophene 34 ± 6

Acetone Formulations

In one embodiment of the process described herein, the solventformulation comprises an aqueous solution of acetone. An aqueoussolution of acetone having a concentration of about 2.5 W % to about 50W % is particularly suitable as a selective solvent formulation forextraction of sulfoxide products. The level of extraction and thespecific concentration of the acetone selective solvent formulationdepend on factors including, but not limited to the sulfur speciation ofthe feed hydrocarbon mixture and whether the target sulfoxide productsto be extracted are non-bulky or bulky. For non-bulky sulfoxide productsthe concentration of the aqueous acetone solution can be about 2.5 W %to about 20 W %, which will extract the non-bulky sulfoxide products,while minimizing co-extraction of certain sulfones, untreatedorganosulfur compounds, non-heteroatom aromatics and other hydrocarbons.For bulky sulfoxide products, the concentration of the aqueous acetonesolution can be about 20 W % to about 50 W %, which will extract thebulky sulfoxide products, while minimizing co-extraction of certainsulfones, non-heteroatom aromatics, untreated organosulfur compounds andother hydrocarbons.

In an extractive simulation, COSMO-RS software was used to simulate γfor selective extraction of oxidized model A fuel by solventformulations of aqueous acetone. Acetone is desirable as a polar organicsolvent due to its low boiling point, thereby facilitating its recoveryand separation from the sulfoxide products.

Table 2A illustrates the activity coefficient of differentconcentrations of aqueous acetone for the compounds listed. Based on theactivity coefficient values in Table 2A, a useful aqueous acetoneselective solvent formulation has a concentration of about 20 W % toabout 30 W % for extraction of DBT sulfoxide, with minimal co-extractionof certain sulfones, untreated organosulfur compounds, aromatics andother hydrocarbons, as shown in FIG. 3. An aqueous acetone selectivesolvent formulation of about 20 W % to about 30 W % is also useful forextraction of thiophene sulfoxide, thiophene sulfone, dibutyl sulfoxideand dibutyl sulfone. If the target sulfoxidation products are primarilythiophene sulfoxide and dibutyl sulfoxide, a useful selective solventformulation can be about 5 W % to about 10 W % aqueous acetone, as shownin FIGS. 4 and 5.

In another extraction simulation, COSMO-RS software was used to simulateγ for formulations of aqueous acetone as extraction solvents foroxidized model B fuel. The results are shown in Table 2B. Activitycoefficient values as shown in Table 2B indicate that certainformulations of aqueous acetone will selectively extract bulky sulfoxideproducts while minimizing co-extraction of their corresponding sulfonesand underlying organosulfur compounds. Based on the activity coefficientvalues in Table 2B, a useful aqueous acetone selective solventformulation has a concentration of about 10 W % to about 30 W % forselective extraction of bulky sulfoxidation products including alkyl anddialkyl derivatives of benzothiophenes and dibenzothiophenes.

In Table 2B, activity coefficients for targeted sulfoxides for whichextraction is favored are marked with an asterisk (“*”), activitycoefficients for non-targeted corresponding sulfones and the underlyingorganosulfur compounds for which co-extraction is minimized are markedwith a pound symbol (“#”).

TABLE 2A Solvent (Acetone W %/Water W %) 0/100 10/90 20/80 30/70 40/6050/50 60/40 70/30 80/20 90/10 100/0 Compound Activity Coefficientdibenzothiophene 320.54 18.92 5.21 2.56 1.65 1.27 1.07 0.99 0.96 1.011.16 5-oxide (DBT sulfoxide) dibenzothiophene 6063.24 330.30 61.56 19.117.92 4.01 2.34 1.51 1.06 0.79 0.63 5,5-dioxide (DBT sulfone)dibenzothiophene (DBT) 7.90E+05 5825.50 399.41 72.97 22.65 9.49 4.902.92 1.92 1.35 1.01 1-butylsulfinyl-butane 51.42 2.86 0.83 0.45 0.330.30 0.29 0.31 0.37 0.48 0.81 (Dibutyl Sulfoxide) 1-butylsulfonyl-butane336.97 38.86 13.20 6.49 3.82 2.51 1.80 1.38 1.11 0.92 0.81 (DibutylSulfone) 1-butylsulfanyl-butane 5.04E+05 4964.16 411.58 86.49 29.0813.07 7.03 4.35 2.92 2.10 1.58 (Dibutyl Sulfide) Thiophene Sulfoxide2.83 1.38 1.09 1.02 1.02 1.05 1.11 1.20 1.32 1.52 1.86 Thiophene Sulfone49.40 21.98 11.47 6.49 4.06 2.75 1.99 1.54 1.25 1.05 0.95 Thiophene2208.35 138.38 29.37 10.80 5.37 3.19 2.14 1.57 1.21 0.98 0.82Naphthalene 4.44E+04 953.37 114.43 29.37 11.36 5.64 3.29 2.16 1.52 1.140.90 Toluene 9798.65 395.44 67.36 21.76 9.87 5.53 3.53 2.48 1.86 1.451.19 nC₁₂ 3.52E+08 4.99E+05 1.60E+04 1939.14 459.44 162.39 72.97 39.2523.57 15.49 10.80

TABLE 2B Solvent (Acetone W %/Water W %) Compound 0/100 10/90 20/8030/70 40/60 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1- 47.00 4.57* 1.77* 1.10 0.84 oxidebenzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1- 988.0095.58^(#) 25.91^(#) 10.23 5.07 sulfone benzo(b)thiophene 1,1-dioxide6-Methylbenzothiophene 6-methyl-1- 1.20E+05 1455.35^(#) 140.47^(#) 32.4611.90 benzo(b)thiophene 2,6- 2,6-dimethyl-1- 88.00 5.64* 1.82* 1.03 0.75Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 1967.00 133.00^(#) 31.30^(#) 11.50 5.45Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide 2,6-2,6-dimethyl-1- 3.87E+05 2958.44^(#) 228.30^(#) 46.29 15.58Dimethylbenzothiophene benzo(b)thiophene 2,3,6- 2,3,6-trimethyl-1-313.00 12.29* 3.13* 1.53 1.01 Trimethylbenzothiophene- benzo(b)thiopheneoxide 1-oxide 2,3,6- 2,3,6-trimethyl-1- 5917.00 250.17^(#) 47.36^(#)15.43 6.78 Trimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,3,6- 2,3,6-trimethyl-1- 1.17E+06 5943.06^(#) 377.69^(#) 68.46 21.43Trimethylbenzothiophene benzo(b)thiophene Dibenzothiophenedibenzothiophene 251.00 12.25* 3.38* 1.70 1.14 oxide 5-oxideDibenzothiophene dibenzothiophene 6267.00 270.83^(#) 48.57^(#) 14.856.18 sulfone 5,5-dioxide Dibenzothiophene dibenzothiophene 6.67E+053900.52^(#) 259.38^(#) 47.64 14.96 4-Methyldibenzothiophene4-methyldibenzothiophene 1542.00 30.51 5.51^(#) 2.18* 1.26 oxide 5-oxide4-Methyldibenzothiophene 4-methyldibenzothiophene 3.90E+04 726.0590.35^(#) 22.74^(#) 8.41 sulfone 5,5-dioxide 4-Methyldibenzothiophene4-methyldibenzothiophene 6.02E+06 1.48E+04 654.23^(#) 94.69^(#) 25.473,6-Dimethyldibenzothiophene 3,6-dimethyldibenzothiophene 718.00 22.314.91* 2.15* 1.31 oxide 5-oxide 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 1.79E+04 476.99 69.03^(#) 18.84^(#) 7.33sulfone 5,5-dioxide 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 1.84E+06 7258.60 401.16^(#) 66.27^(#) 19.434,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene 1664.00 33.226.00* 2.37* 1.35 oxide 5-oxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 4.41E+04 793.55 96.69^(#) 24.02^(#) 8.80sulfone 5,5-dioxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 5.81E+06 1.47E+04 652.00^(#) 94.87^(#)25.60 2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene 2.47E+0347.35 8.19* 3.09* 1.70 oxide 5-oxide 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 3.74E+04 709.28 90.18^(#) 23.21^(#) 8.75sulfone 5,5-dioxide 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 5.04E+06 1.36E+04 626.15^(#) 93.30^(#)25.60 2,4,7- 2,4,7- 4095.00 52.04 7.68* 2.72* 1.46Trimethyldibenzothiophene trimethyldibenzothiophene oxide 5-oxide 2,4,7-2,4,7- 9.72E+04 1228.80 129.67^(#) 29.82^(#) 10.41Trimethyldibenzothiophene trimethyldibenzothiophene sulfone 5,5-dioxide2,4,7- 2,4,7- 2.05E+07 3.17E+04 1120.10^(#) 142.36^(#) 35.18Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 1706.00 34.51 6.24*2.46* 1.40 oxide 5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene5.43E+04 869.35 97.65^(#) 22.99^(#) 8.13 sulfone 5,5-dioxide4-Ethyldibenzothiophene 4-ethyldibenzothiophene 5.28E+06 1.35E+04608.55^(#) 89.38^(#) 24.28 4-Propyldibenzothiophene4-propyldibenzothiophene 4103.00 52.77 7.74* 2.71* 1.44 oxide 5-oxide4-Propyldibenzothiophene 4-propyldibenzothiophene 1.60E+05 1587.37141.28^(#) 28.98^(#) 9.36 sulfone 5,5-dioxide 4-Propyldibenzothiophene4-propyldibenzothiophene 1.72E+07 2.70E+04 958.28^(#) 122.09^(#) 30.202-Butyldibenzothiophene 2-butyldibenzothiophene 1.43E+04 102.03 11.28*3.36* 1.61 oxide 5-oxide 2-Butyldibenzothiophene 2-butyldibenzothiophene3.38E+05 2365.51 180.45^(#) 33.61^(#) 10.13 sulfone 5,5-dioxide2-Butyldibenzothiophene 2-butyldibenzothiophene 7.58E+07 6.46E+041684.53^(#) 177.85^(#) 38.80 2-Pentyldibenzothiophene2-pentyldibenzothiophene 5.25E+04 227.33 19.57 5.00* 2.15 oxide 5-oxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1.07E+06 4590.61274.96 44.35^(#) 12.15 sulfone 5,5-dioxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 2.67E+08 1.38E+05 2815.56 256.93* 50.911-Phenyldibenzothiophene 1-Phenyldibenzothiophene 1.17E+04 101.62 12.02*3.68* 1.78 oxide 5-oxide 1-Phenyldibenzothiophene1-Phenyldibenzothiophene 3.46E+05 2600.07 198.66^(#) 36.59^(#) 10.91sulfone 5,5-dioxide 1-Phenyldibenzothiophene 1-phenyldibenzothiophene4.77E+07 4.84E+04 1349.88^(#) 147.29^(#) 32.74 4-Phenyldibenzothiophene4-phenyldibenzothiophene 6.25E+04 373.87 33.44 8.20* 3.32 oxide 5-oxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 3.59E+05 2629.76194.47 35.14^(#) 10.37 sulfone 5,5-dioxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene 5.26E+07 5.09E+04 1359.61 143.33^(#) 31.03Dodecane Dodecane 6.02E+08 4.55E+05 1.28E+04 1495.10 355.60 Naphthalenebicyclo[4.4.0]deca- 5.55E+04 897.40 100.30 25.30 9.80 1,3,5,7,9-penteneDibutyl sulfoxide 1-butylsulfinyl-butane 49.90 2.30* 0.70 0.40 0.30Dibutyl sulfone 1-butylsulfonyl-butane 324.80 32.00^(#) 11.00 5.50 3.30Dibutyl sulfide 1-butylsulfanyl-butane 5.23E+05 4250.30^(#) 364.60 79.7028.20 Thiophene sulfide tetrahydrothiophene 250.10 12.20 3.40 1.70 1.101-oxide Thiophene sulfone tetrahydrothiophene 6248.60 270.60 48.60 14.806.20 1,1-dioxide Thiophene Thiophene 6.64E+05 3892.30 258.70 47.50 14.90Toluene Methylbenzene 2.00 1.00 0.80 0.80 0.80 Solvent (Acetone W%/Water W %) Compound 50/50 60/40 70/30 80/20 90/10 100/0 Common NameIUPAC Activity Coefficient 6-Methylbenzothiophene 6-methyl-1- 0.73 0.680.67 0.70 0.77 0.93 oxide benzo(b)thiophene 1-oxide6-Methylbenzothiophene 6-methyl-1- 2.93 1.89 1.33 1.00 0.78 0.65 sulfonebenzo(b)thiophene 1,1-dioxide 6-Methylbenzothiophene 6-methyl-1- 5.743.29 2.13 1.49 1.12 0.87 benzo(b)thiophene 2,6- 2,6-dimethyl-1- 0.630.59 0.58 0.61 0.68 0.86 Dimethylbenzothiophene benzo(b)thiophene oxide1-oxide 2,6- 2,6-dimethyl-1- 3.05 1.93 1.33 0.98 0.77 0.62Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide 2,6-2,6-dimethyl-1- 7.07 3.88 2.42 1.66 1.21 0.93 Dimethylbenzothiophenebenzo(b)thiophene 2,3,6- 2,3,6-trimethyl-1- 0.79 0.69 0.65 0.65 0.700.86 Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide 2,3,6-2,3,6-trimethyl-1- 3.62 2.20 1.48 1.07 0.82 0.65 Trimethylbenzothiophenebenzo(b)thiophene sulfone 1,1-dioxide 2,3,6- 2,3,6-trimethyl-1- 9.244.89 2.97 1.98 1.42 1.07 Trimethylbenzothiophene benzo(b)thiopheneDibenzothiophene dibenzothiophene 0.90 0.78 0.73 0.73 0.78 0.91 oxide5-oxide Dibenzothiophene dibenzothiophene 3.16 1.86 1.22 0.86 0.65 0.52sulfone 5,5-dioxide Dibenzothiophene dibenzothiophene 6.45 3.41 2.071.38 0.99 0.75 4-Methyldibenzothiophene 4-methyldibenzothiophene 0.900.73 0.65 0.63 0.66 0.79 oxide 5-oxide 4-Methyldibenzothiophene4-methyldibenzothiophene 3.96 2.21 1.38 0.94 0.69 0.53 sulfone5,5-dioxide 4-Methyldibenzothiophene 4-methyldibenzothiophene 9.86 4.812.74 1.74 1.20 0.87 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 0.96 0.80 0.72 0.69 0.72 0.83 oxide 5-oxide3,6-Dimethyldibenzothiophene 3,6-dimethyldibenzothiophene 3.58 2.05 1.310.91 0.67 0.53 sulfone 5,5-dioxide 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 7.99 4.08 2.41 1.57 1.11 0.824,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene 0.96 0.77 0.690.66 0.68 0.79 oxide 5-oxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 4.12 2.28 1.43 0.97 0.71 0.55 sulfone5,5-dioxide 4,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene9.93 4.85 2.77 1.76 1.21 0.89 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 1.15 0.90 0.77 0.71 0.72 0.80 oxide 5-oxide2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene 4.20 2.37 1.501.03 0.76 0.59 sulfone 5,5-dioxide 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 10.05 4.96 2.85 1.82 1.26 0.92 2,4,7-2,4,7- 0.99 0.78 0.68 0.64 0.67 0.79 Trimethyldibenzothiophenetrimethyldibenzothiophene oxide 5-oxide 2,4,7- 2,4,7- 4.71 2.54 1.561.04 0.75 0.57 Trimethyldibenzothiophene trimethyldibenzothiophenesulfone 5,5-dioxide 2,4,7- 2,4,7- 12.83 5.99 3.30 2.04 1.37 0.98Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 0.98 0.79 0.69 0.66 0.670.76 oxide 5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene 3.722.03 1.25 0.84 0.61 0.47 sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 9.47 4.65 2.66 1.70 1.17 0.864-Propyldibenzothiophene 4-propyldibenzothiophene 0.96 0.75 0.65 0.610.62 0.71 oxide 5-oxide 4-Propyldibenzothiophene4-propyldibenzothiophene 4.02 2.09 1.24 0.81 0.57 0.43 sulfone5,5-dioxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 11.02 5.152.84 1.76 1.18 0.85 2-Butyldibenzothiophene 2-butyldibenzothiophene 1.010.75 0.63 0.57 0.57 0.65 oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene 4.12 2.05 1.18 0.75 0.52 0.38 sulfone5,5-dioxide 2-Butyldibenzothiophene 2-butyldibenzothiophene 12.95 5.652.96 1.76 1.15 0.80 2-Pentyldibenzothiophene 2-pentyldibenzothiophene1.25 0.87 0.69 0.60 0.58 0.63 oxide 5-oxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 4.62 2.19 1.21 0.75 0.51 0.37 sulfone5,5-dioxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 15.87 6.593.31 1.91 1.21 0.83 1-Phenyldibenzothiophene 1-Phenyldibenzothiophene1.12 0.83 0.69 0.63 0.62 0.69 oxide 5-oxide 1-Phenyldibenzothiophene1-Phenyldibenzothiophene 4.40 2.18 1.24 0.79 0.55 0.40 sulfone5,5-dioxide 1-Phenyldibenzothiophene 1-phenyldibenzothiophene 11.06 4.872.56 1.53 1.00 0.70 4-Phenyldibenzothiophene 4-phenyldibenzothiophene1.80 1.17 0.86 0.70 0.62 0.61 oxide 5-oxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene 4.16 2.05 1.17 0.74 0.51 0.38 sulfone5,5-dioxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 10.27 4.452.31 1.37 0.89 0.62 Dodecane Dodecane 127.10 58.60 32.00 19.70 13.209.40 Naphthalene bicyclo[4.4.0]deca- 4.90 2.90 1.90 1.40 1.00 0.801,3,5,7,9-pentene Dibutyl sulfoxide 1-butylsulfinyl-butane 0.30 0.300.30 0.40 0.50 0.90 Dibutyl sulfone 1-butylsulfonyl-butane 2.20 1.601.20 1.00 0.90 0.80 Dibutyl sulfide 1-butylsulfanyl-butane 13.20 7.404.70 3.20 2.40 1.80 Thiophene sulfide tetrahydrothiophene 0.90 0.80 0.700.70 0.80 0.90 1-oxide Thiophene sulfone tetrahydrothiophene 3.20 1.901.20 0.90 0.60 0.50 1,1-dioxide Thiophene Thiophene 6.40 3.40 2.10 1.401.00 0.70 Toluene Methylbenzene 0.90 0.90 1.00 1.10 1.30 1.60

Methanol Formulations

In another embodiment of the process described herein, the solventformulation comprises an aqueous solution of methanol. An aqueoussolution of methanol having a concentration of about 10 W % to about 70W % is particularly useful as a selective solvent formulation forextraction of sulfoxide products. The level of extraction and thespecific concentration of the methanol selective solvent formulationdepend on factors including but not limited to the sulfur speciation ofthe feed hydrocarbon mixture and whether the target sulfoxide productsto be extracted are non-bulky or bulky. For non-bulky sulfoxideproducts, the concentration of the aqueous methanol solution can beabout 10 W % to about 30 W %, which will extract the non-bulky sulfoxideproducts, while minimizing co-extraction of certain sulfones, untreatedorganosulfur compounds, non-heteroatom aromatics and other hydrocarbons.For bulky sulfoxide products, the concentration of the aqueous methanolsolution can be about 30 W % to about 70 W %, which will extract thebulky sulfoxide products, while minimizing co-extraction of certainsulfones, non-heteroatom aromatics, untreated organosulfur compounds andother hydrocarbons.

In an extractive simulation, COSMO-RS software was used to simulate γfor selective extraction of oxidized model A fuel by solventformulations of aqueous methanol. Methanol is desirable as a polarorganic solvent due to its low boiling point, thereby facilitatingrecovery and separation from the sulfoxide products.

Table 3A illustrates the activity coefficient of differentconcentrations of aqueous methanol for the compounds listed. Based onthe activity coefficient values in Table 3A, a useful aqueous methanolselective solvent formulation has a concentration of about 30 W % toabout 70 W % for extraction of DBT sulfoxide with minimal co-extractionof certain sulfones, untreated organosulfur compounds, aromatics andother hydrocarbons, as shown in FIG. 6. An aqueous methanol selectivesolvent formulation of about 30 W % to about 70 W % is also useful forextraction of thiophene sulfoxide, thiophene sulfone, dibutyl sulfoxideand dibutyl sulfone. If the target sulfoxidation products are primarilythiophene sulfoxide and dibutyl sulfoxide, a suitable selective solventformulation can be about 10 W % to about 30 W % aqueous methanol, asshown in FIGS. 7 and 8.

In another extraction simulation, COSMO-RS software was used to simulateγ for formulations of aqueous methanol as extraction solvents foroxidized model B fuel. The results are shown in Table 3B. Activitycoefficient values as shown in Table 3B indicate that certainformulations of aqueous methanol will selectively extract bulkysulfoxide products while minimizing co-extraction of their correspondingsulfones and underlying organosulfur compounds. Based on the activitycoefficient values in Table 3B, a useful methanol selective solventformulation has a concentration of about 20 W % to about 60 W % forselective extraction of bulky sulfoxide products including alkyl anddialkyl derivatives of benzothiophenes and dibenzothiophenes.

In Table 3B, activity coefficients for targeted sulfoxides for whichextraction is favored are marked with an asterisk (“*”), activitycoefficients for non-targeted corresponding sulfones and the underlyingorganosulfur compounds for which co-extraction is minimized are markedwith a pound symbol (“#”).

Note that for extraction of certain bulky sulfoxide products, such as6-methylbenzothiophene oxide and 2,6-dimethylbenzothiophene oxide,selective solvent formulations can contain as little as 10 W % methanol,but selective extraction of other bulky sulfoxide products will be verylimited.

It is noted that although the activity coefficient values for certainhigh concentration methanol formulations indicate favorable extractionof certain bulky or non-bulky sulfoxidation products (includingsulfoxides and sulfones), these high concentration methanol formulations(e.g., greater than 70 W %) also extract untargeted species andtherefore are not particularly desirable for selective extraction of abroad array of organosulfur oxidation products.

TABLE 3A Solvent (Methanol W %/Water W %) 0/100 10/90 20/80 30/70 40/6050/50 60/40 70/30 80/20 90/10 100/0 Compound Activity Coefficientdibenzothiophene 5-oxide 250.10 31.30 9.80 4.90 3.20 2.40 1.90 1.70 1.501.40 1.30 (DBT sulfoxide) dibenzothiophene 5,5-dioxide 6248.00 835.50256.10 116.90 65.80 41.70 28.60 20.60 15.40 11.90 9.40 (DBT sulfone)dibenzothiophene (DBT) 6.64E+05 3.15E+04 4355.00 1074.00 375.20 164.6084.70 48.90 30.80 20.70 14.70 1-butylsulfinyl-butane 49.90 5.40 1.500.70 0.50 0.30 0.30 0.30 0.20 0.20 0.20 (Dibutyl Sulfoxide)1-butylsulfonyl-butane 324.80 56.50 22.30 13.10 9.40 7.40 6.30 5.50 4.804.30 3.90 (Dibutyl Sulfone) 1-butylsulfanyl-butane 5.23E+05 2.49E+043611.00 956.20 359.40 168.90 92.40 56.40 37.20 26.20 19.30 (DibutylSulfide) Thiophene Sulfoxide 122.40 44.00 23.80 15.70 11.50 8.90 7.206.00 5.10 4.40 3.80 Thiophene Sulfone 42.80 25.60 19.70 16.60 14.3012.50 10.90 9.50 8.20 7.20 6.30 Thiophene 1819.00 358.70 122.10 56.2031.20 19.50 13.30 9.60 7.30 5.80 4.70 Naphthalene 5552.00 4789.10 974.70315.50 134.90 69.20 40.40 25.80 17.70 12.80 9.70 Toluene 1.26E+041574.10 407.80 157.00 76.60 43.70 27.70 19.00 13.90 10.60 8.40 nC₁₂3.99E+07 8.42E+05 7.25E+04 1.33E+04 3798.00 1451.00 675.00 363.00 216.60140.20 96.70

TABLE 3B Solvent (Methanol W %/Water W %) Compound 0/100 10/90 20/8030/70 40/60 50/50 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1- 47.00 8.64* 3.42* 2.01* 1.47* 1.21*oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-988.00 206.02^(#) 83.59^(#) 46.52^(#) 30.42^(#) 21.77^(#) sulfonebenzo(b)thiophene 1,1-dioxide 6-Methylbenzothiophene 6-methyl-1-1.20E+05 8531.02^(#) 1523.93^(#) 450.32^(#) 180.31^(#) 88.16^(#)benzo(b)thiophene 2,6- 2,6-dimethyl-1- 88.00 12.15* 4.03* 2.11* 1.42*1.11* Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 1967.00 313.60^(#) 108.81^(#) 55.00^(#) 33.79^(#)23.18^(#) Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,6- 2,6-dimethyl-1- 3.87E+05  2.04E+04^(#) 3008.12^(#) 780.51^(#)284.45^(#) 129.55^(#) Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 313.00 31.43 8.53* 3.89* 2.36* 1.70*Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide 2,3,6-2,3,6-trimethyl-1- 5917.00 689.22 195.80^(#) 86.31^(#) 48.04^(#)30.62^(#) Trimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,3,6- 2,3,6-trimethyl-1- 1.17E+06 4.70E+04 5852.93^(#) 1353.94^(#)454.44^(#) 194.61^(#) Trimethylbenzothiophene benzo(b)thiopheneDibenzothiophene dibenzothiophene 251.00 31.30 9.80* 4.90* 3.20* 2.40*oxide 5-oxide Dibenzothiophene dibenzothiophene 6267.00 835.50256.10^(#) 116.90^(#) 65.80^(#) 41.70^(#) sulfone 5,5-dioxideDibenzothiophene dibenzothiophene 6.67E+05 3.15E+04 4355.30^(#)1074.00^(#) 375.20^(#) 164.60^(#) 4-Methyldibenzothiophene4-methyldibenzothiophene 718.00 65.39 16.66 7.22* 4.20* 2.91* oxide5-oxide 4-Methyldibenzothiophene 4-methyldibenzothiophene 1.79E+041683.15 412.99 162.14^(#) 82.02^(#) 48.22^(#) sulfone 5,5-dioxide4-Methyldibenzothiophene 4-methyldibenzothiophene 1.84E+06 6.58E+047615.56 1668.71^(#) 536.41^(#) 221.64^(#) 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 1664.00 103.44 21.82 8.36* 4.46* 2.91*oxide 5-oxide 3,6-Dimethyldibenzothiophene 3,6-dimethyldibenzothiophene4.41E+04 2826.41 593.29 211.11^(#) 99.99^(#) 56.15^(#) sulfone5,5-dioxide 3,6-Dimethyldibenzothiophene 3,6-dimethyldibenzothiophene5.81E+06 1.58E+05 1.51E+04 2905.71^(#) 849.28^(#) 326.62^(#)4,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene 2468.00 112.2823.74 9.09* 4.85* 3.16* oxide 5-oxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 3.74E+04 3138.83 649.28 228.27^(#) 107.06*59.63* sulfone 5,5-dioxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 5.04E+06 1.55E+05 1.49E+04 2875.57^(#)843.51* 325.30* 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 1542.00 165.30 34.52 13.01* 6.81* 4.34*oxide 5-oxide 2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene3.90E+04 2732.76 575.32 204.94^(#) 97.20^(#) 54.71^(#) sulfone5,5-dioxide 2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene6.02E+06 1.39E+05 1.37E+04 2702.30^(#) 804.33^(#) 313.82^(#) 2,4,7-2,4,7- 4095.00 203.36 35.61 12.04* 5.89* 3.60* Trimethyldibenzothiophenetrimethyldibenzothiophene oxide 5-oxide 2,4,7- 2,4,7- 9.72E+04 5321.64945.96 302.83^(#) 133.56^(#) 71.32^(#) Trimethyldibenzothiophenetrimethyldibenzothiophene sulfone 5,5-dioxide 2,4,7- 2,4,7- 2.05E+073.98E+05 3.14E+04 5291.32^(#) 1407.93^(#) 504.49^(#)Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 1706.00 117.52 25.179.71* 5.20* 3.39* oxide 5-oxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.43E+04 3744.51 749.52 254.85^(#) 115.83^(#)62.73^(#) sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.28E+06 1.42E+05 1.38E+04 2690.48^(#)794.24^(#) 307.85^(#) 4-Propyldibenzothiophene 4-propyldibenzothiophene4103.00 210.79 37.63 12.85* 6.31* 3.86* oxide 5-oxide4-Propyldibenzothiophene 4-propyldibenzothiophene 1.60E+05 8114.041338.67 398.99^(#) 164.81^(#) 83.04^(#) sulfone 5,5-dioxide4-Propyldibenzothiophene 4-propyldibenzothiophene 1.72E+07 3.40E+052.72E+04 4625.07^(#) 1237.88^(#) 445.33^(#) 2-Butyldibenzothiophene2-butyldibenzothiophene 1.43E+04 502.20 70.76 20.60 9.03* 5.07* oxide5-oxide 2-Butyldibenzothiophene 2-butyldibenzothiophene 3.38E+051.33E+04 1900.63 520.80 203.69^(#) 98.74^(#) sulfone 5,5-dioxide2-Butyldibenzothiophene 2-butyldibenzothiophene 7.58E+07 1.03E+066.45E+04 9267.92 2188.34^(#) 714.84^(#) 2-Pentyldibenzothiophene2-pentyldibenzothiophene 5.25E+04 1344.27 155.01 39.28 15.55* 8.07*oxide 5-oxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1.07E+063.08E+04 3626.00 867.33 307.18^(#) 138.09^(#) sulfone 5,5-dioxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 2.67E+08 2.64E+061.35E+05 1.70E+04 3619.77^(#) 1095.31^(#) 1-Phenyldibenzothiophene1-Phenyldibenzothiophene 1.17E+04 482.62 74.97 23.24 10.62* 6.14* oxide5-oxide 1-Phenyldibenzothiophene 1-Phenyldibenzothiophene 3.46E+051.48E+04 2231.04 626.34 247.84^(#) 120.69^(#) sulfone 5,5-dioxide1-Phenyldibenzothiophene 1-phenyldibenzothiophene 4.77E+07 7.44E+055.11E+04 7787.89 1917.06^(#) 645.22^(#) 4-Phenyldibenzothiophene4-phenyldibenzothiophene 6.25E+04 2209.02 300.54 82.49 33.71 17.59 oxide5-oxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 3.59E+051.57E+04 2341.14 649.49 253.73 122.13 sulfone 5,5-dioxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 5.26E+07 8.09E+055.48E+04 8252.85 2006.56 667.57 Dodecane Dodecane 6.02E+08 8.42E+057.25E+04 13274.20 3798.80 1451.10 Naphthalene bicyclo[4.4.0]deca-5.55E+04 4789.10 974.70 315.50 134.90 69.20 1,3,5,7,9-pentene Dibutylsulfoxide 1-butylsulfinyl-butane 49.90 5.40^(#) 1.50^(#) 0.70 0.50 0.30Dibutyl sulfone 1-butylsulfonyl-butane 324.80 56.50* 22.30* 13.10 9.407.40 Dibutyl sulfide 1-butylsulfanyl-butane 5.23E+05 24853.60* 3611.60*956.20 359.40 168.90 Thiophene sulfide tetrahydrothiophene 2.00 44.0023.80 15.70^(#) 11.50 8.90 1-oxide Thiophene sulfone tetrahydrothiophene43.10 25.60 19.70 16.60* 14.30 12.50 1,1-dioxide Thiophene Thiophene1819.20 358.70 122.10 56.20* 31.20 19.50 Toluene Methylbenzene 1.26E+041574.10 407.80 157.00 76.60 43.70 Solvent (Methanol W %/Water W %)Compound 60/40 70/30 80/20 90/10 100/0 Common Name IUPAC ActivityCoefficient 6-Methylbenzothiophene 6-methyl-1- 1.07* 0.99 0.95 0.92 0.90oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-16.45^(#) 12.89 10.37 8.52 7.12 sulfone benzo(b)thiophene 1,1-dioxide6-Methylbenzothiophene 6-methyl-1- 49.48^(#) 30.71 20.56 14.60 10.88benzo(b)thiophene 2,6- 2,6-dimethyl-1- 0.94* 0.85 0.79 0.75 0.73Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 17.00* 13.04 10.32 8.37 6.92 Dimethylbenzothiophenebenzo(b)thiophene sulfone 1,1-dioxide 2,6- 2,6-dimethyl-1- 68.79^(#)40.84 26.38 18.17 13.20 Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 1.35* 1.15 1.03 0.95 0.89 Trimethylbenzothiophene-benzo(b)thiophene oxide 1-oxide 2,3,6- 2,3,6-trimethyl-1- 21.24^(#)15.59 11.93 9.40 7.61 Trimethylbenzothiophene benzo(b)thiophene sulfone1,1-dioxide 2,3,6- 2,3,6-trimethyl-1- 98.51^(#) 56.32 35.27 23.69 16.85Trimethylbenzothiophene benzo(b)thiophene Dibenzothiophenedibenzothiophene 1.90* 1.70* 1.50 1.40 1.30 oxide 5-oxideDibenzothiophene dibenzothiophene 28.60^(#) 20.60^(#) 15.40 11.90 9.40sulfone 5,5-dioxide Dibenzothiophene dibenzothiophene 84.70^(#)48.90^(#) 30.80 20.70 14.70 4-Methyldibenzothiophene4-methyldibenzothiophene 2.25* 1.86* 1.62 1.45 1.33 oxide 5-oxide4-Methyldibenzothiophene 4-methyldibenzothiophene 31.21^(#) 21.59^(#)15.69 11.83 9.20 sulfone 5,5-dioxide 4-Methyldibenzothiophene4-methyldibenzothiophene 108.84^(#) 60.61^(#) 37.09 24.41 17.063,6-Dimethyldibenzothiophene 3,6-dimethyldibenzothiophene 2.15* 1.72*1.46* 1.28 1.16 oxide 5-oxide 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 35.15^(#) 23.71^(#) 16.89^(#) 12.54 9.64sulfone 5,5-dioxide 3,6-Dimethyldibenzothiophene3,6-dimethyldibenzothiophene 151.65^(#) 80.75^(#) 47.65^(#) 30.42 20.734,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene 2.33* 1.86*1.57* 1.38 1.24 oxide 5-oxide 4,6-Dimethyldibenzothiophene4,6-dimethyldibenzothiophene 37.08* 24.88* 17.64* 13.05 10.00 sulfone5,5-dioxide 4,6-Dimethyldibenzothiophene 4,6-dimethyldibenzothiophene151.37* 80.75* 47.72* 30.51 20.81 2,4-Dimethyldibenzothiophene2,4-dimethyldibenzothiophene 3.1 2.46* 2.04* 1.76 1.56 oxide 5-oxide2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene 34.36^(#)23.27^(#) 16.65^(#) 12.42 9.60 sulfone 5,5-dioxide2,4-Dimethyldibenzothiophene 2,4-dimethyldibenzothiophene 147.43^(#)79.28^(#) 47.17^(#) 30.34 20.79 2,4,7- 2,4,7- 2.53* 1.95* 1.60* 1.381.22 Trimethyldibenzothiophene trimethyldibenzothiophene oxide 5-oxide2,4,7- 2,4,7- 43.02^(#) 28.21^(#) 19.66^(#) 14.34 10.86Trimethyldibenzothiophene trimethyldibenzothiophene sulfone 5,5-dioxide2,4,7- 2,4,7- 221.66^(#) 112.94^(#) 64.29^(#) 39.85 26.48Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 2.50* 2.00* 1.69* 1.481.33 oxide 5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene38.06^(#) 24.99^(#) 17.40^(#) 12.66 9.57 sulfone 5,5-dioxide4-Ethyldibenzothiophene 4-ethyldibenzothiophene 143.83^(#) 76.98^(#)45.61^(#) 29.23 19.97 4-Propyldibenzothiophene 4-propyldibenzothiophene2.71* 2.09* 1.71* 1.46 1.29 oxide 5-oxide 4-Propyldibenzothiophene4-propyldibenzothiophene 47.59^(#) 29.86^(#) 20.02^(#) 14.12 10.40sulfone 5,5-dioxide 4-Propyldibenzothiophene 4-propyldibenzothiophene196.19^(#) 100.14^(#) 57.07^(#) 35.40 23.54 2-Butyldibenzothiophene2-butyldibenzothiophene 3.34* 2.44* 1.92* 1.59 1.36 oxide 5-oxide2-Butyldibenzothiophene 2-butyldibenzothiophene 54.95^(#) 33.66^(#)22.11^(#) 15.32 11.09 sulfone 5,5-dioxide 2-Butyldibenzothiophene2-butyldibenzothiophene 291.61^(#) 139.81^(#) 75.64^(#) 44.91 28.772-Pentyldibenzothiophene 2-pentyldibenzothiophene 4.99* 3.46* 2.61*2.08* 1.73 oxide 5-oxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 72.41^(#) 42.27^(#) 26.70^(#) 17.89^(#) 12.61sulfone 5,5-dioxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene420.66^(#) 192.10^(#) 99.86^(#) 57.33^(#) 35.70 1-Phenyldibenzothiophene1-Phenyldibenzothiophene 4.13* 3.06* 2.43* 2.02* 1.74 oxide 5-oxide1-Phenyldibenzothiophene 1-Phenyldibenzothiophene 67.23* 41.14^(#)26.97^(#) 18.64^(#) 13.47 sulfone 5,5-dioxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 269.16* 131.25^(#) 71.95^(#) 43.16^(#) 27.874-Phenyldibenzothiophene 4-phenyldibenzothiophene 10.75* 7.31* 5.37*4.16* 3.36 oxide 5-oxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene 67.37^(#) 40.89^(#) 26.63^(#) 18.31^(#) 13.17sulfone 5,5-dioxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene275.51^(#) 133.03^(#) 72.27^(#) 42.99^(#) 27.55 Dodecane Dodecane 675.90363.00 216.60 140.20 96.70 Naphthalene bicyclo[4.4.0]deca- 40.40 25.8017.70 12.80 9.70 1,3,5,7,9-pentene Dibutyl sulfoxide1-butylsulfinyl-butane 0.30 0.30 0.20 0.20 0.20 Dibutyl sulfone1-butylsulfonyl-butane 6.30 5.50 4.80 4.30 3.90 Dibutyl sulfide1-butylsulfanyl-butane 92.40 56.40 37.20 26.20 19.30 Thiophene sulfidetetrahydrothiophene 7.20 6.00 5.10 4.40 3.80 1-oxide Thiophene sulfonetetrahydrothiophene 10.90 9.50 8.20 7.20 6.30 1,1-dioxide ThiopheneThiophene 13.30 9.60 7.30 5.80 4.70 Toluene Methylbenzene 27.70 19.0013.90 10.60 8.40

Acetonitrile Formulations

In still another embodiment of the present invention, the solventformulation comprises an aqueous solution of acetonitrile. An aqueoussolution of acetonitrile having a concentration of about 2.5 W % toabout 40 W % is particularly useful as a selective solvent formulationfor extraction of sulfoxide products, and an aqueous solution ofacetonitrile having a concentration of about 40 W % to about 60 W % isparticularly useful for extraction of bulky sulfoxidation products,i.e., sulfoxides and sulfones. The level of extraction and the specificconcentration of the selective solvent formulation depend on factorsincluding, but not limited to the sulfur speciation of the feedhydrocarbon mixture and whether the target sulfoxide products orsulfoxidation products to be extracted are non-bulky or bulky. Fornon-bulky sulfoxide products, the concentration of the aqueousacetonitrile solution can be about 2.5 W % to about 30 W %, which willextract the non-bulky sulfoxides and also thiophene sulfone, whileminimizing co-extraction of other sulfones, untreated organosulfurcompounds, non-heteroatom aromatics and other hydrocarbons. For bulkysulfoxide products and/or bulky sulfoxidation products, theconcentration of the aqueous acetonitrile solution can be about 30 W %to about 60 W %, which will extract the bulky sulfoxide products and/orbulky sulfoxidation products, while minimizing co-extraction ofnon-heteroatom aromatics, untreated organosulfur compounds and otherhydrocarbons.

In an extractive simulation, COSMO-RS software was used to simulate γfor selective extraction of oxidized model A fuel by solventformulations of aqueous acetonitrile. Acetonitrile is desirable as apolar organic solvent due to its low boiling point, thereby facilitatingrecovery and separation from the sulfoxide products or the sulfoxidationproducts.

Table 4A illustrates the activity coefficient of differentconcentrations of aqueous acetonitrile. Based on the activitycoefficient values in Table 4A, a useful aqueous acetonitrile selectivesolvent formulation has a concentration of about 20 W % to about 40 W %for extraction of DBT sulfoxide, with minimal co-extraction of certainsulfones, untreated organosulfur compounds, aromatics and otherhydrocarbons, as shown in FIG. 9. It is also apparent from FIG. 9 andthe data in Table 4A that a suitable concentration of acetonitrile isabout 40 W % to about 60 W % for extraction of DBT sulfoxide combinedwith DBT sulfone, with minimal co-extraction of aromatics, untreatedorganosulfur compounds and other hydrocarbons. An aqueous acetonitrileselective solvent formulation of about 40 W % to about 60 W % is alsouseful for extraction of thiophene sulfoxide, thiophene sulfone, dibutylsulfoxide and dibutyl sulfone. If the target species are primarilynon-bulky sulfoxide products such as thiophene sulfoxide and dibutylsulfoxide, and also thiophene sulfone, a suitable selective solventformulation can be about 5 W % to about 20 W % aqueous acetonitrile, asshown in FIGS. 10 and 11.

In another extraction simulation, COSMO-RS software was used to simulateγ for formulations of aqueous acetonitrile as extraction solvents foroxidized model B fuel. The results are shown in Table 4B. Activitycoefficient values as shown in Table 4B indicate that certainformulations of aqueous acetonitrile will selectively extract bulkysulfoxide products while minimizing co-extraction of their correspondingsulfones and underlying organosulfur compounds. In addition, activitycoefficient values as shown in Table 4B indicate that certainformulations of aqueous acetonitrile will selectively extract bulkysulfoxidation products, including sulfoxides and sulfones, with minimalco-extraction of aromatics, untreated organosulfur compounds and otherhydrocarbons. Based on the activity coefficient values in Table 4B, auseful acetonitrile selective solvent formulation has a concentration ofabout 10 W % to about 40 W % for selective extraction of bulky sulfoxideproducts including alkyl and dialkyl derivatives of benzothiophenes anddibenzothiophenes. In addition, aqueous acetonitrile selective solventformulations of about 40 W % to about 60 W % are also useful forextraction of bulky sulfoxidation products including sulfoxides andsulfones with minimal co-extraction of aromatics, untreated organosulfurcompounds and other hydrocarbons.

In Table 4B, activity coefficients for targeted sulfoxides for whichextraction is favored are marked with an asterisk (“*”), activitycoefficients for non-targeted underlying organosulfur compounds and incertain cases corresponding sulfones for which co-extraction isminimized are marked with a pound symbol (“#”). Furthermore, activitycoefficients for targeted sulfones for which extraction is favored(i.e., in combination with corresponding sulfoxides) are marked with aletter “C”.

It is noted that although the activity coefficient values for certainhigh concentration acetonitrile formulations indicate favorableextraction of certain bulky or non-bulky sulfoxidation products(including sulfoxides and sulfones), such as products of2-butyldibenzothiophene, 2-pentyldibenzothiophene and dibutyl sulfide,these high concentration acetonitrile formulations (e.g., greater than60 W %) also extract untargeted species and therefore are notparticularly desirable for selective extraction of a broad array oforganosulfur oxidation products.

TABLE 4A Solvent (Acetonitrile W %/Water W %) 0/100 10/90 20/80 30/7040/60 50/50 60/40 70/30 80/20 90/10 100/0 Compound Activity Coefficientdibenzothiophene 5-oxide 321.00 34.10 8.41 3.56 2.08 1.46 1.19 1.07 1.051.14 1.48 (DBT sulfoxide) dibenzothiophene 5,5-dioxide 6063.00 492.7087.40 26.00 10.70 5.47 3.25 2.14 1.52 1.16 0.93 (DBT sulfone)dibenzothiophene (DBT) 7.90E+05 1.57E+04 1300.00 247.00 75.90 31.5016.00 9.21 5.93 4.10 2.97 1-butylsulfinyl-butane 51.40 10.40 3.71 2.031.45 1.22 1.17 1.26 1.49 2.05 4.10 (Dibutyl Sulfoxide)1-butylsulfonyl-butane 337.00 99.50 38.50 19.70 12.10 8.41 6.42 5.264.53 4.06 3.90 (Dibutyl Sulfone) 1-butylsulfanyl-butane 5.04E+052.72E+04 3752.00 963.00 358.00 1701.00 94.60 59.70 40.80 29.40 22.40(Dibutyl Sulfide) Thiophene Sulfoxide 2.83 1.35 0.86 0.68 0.61 0.59 0.610.66 0.76 0.90 1.25 Thiophene Sulfone 49.40 16.90 7.46 4.10 2.61 1.841.40 1.13 0.95 0.84 0.77 Thiophene 2208.00 217.00 49.40 18.34 9.12 5.373.53 2.53 1.93 1.54 1.27 Naphthalene 4.44E+04 2392.00 361.00 100.0040.00 20.10 11.70 7.54 5.31 3.94 3.06 Toluene 9799.00 973.00 215.0076.70 36.20 20.70 13.30 9.39 6.96 5.47 4.44 nC₁₂ 3.52E+08 8.71E+067.29E+05 1.33E+05 3.93E+04 1.58E+04 7708.00 4359.00 2724.00 1845.001313.00

TABLE 4B Solvent (Acetonitrile W %/Water W %) Compound 0/100 10/90 20/8030/70 40/60 50/50 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1- 47.00 8.53*   2.95*   1.55* 1.04*0.82  oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-988.00 144.56^(#)   36.35^(#)  13.57 ^(C)  6.55 ^(C) 3.75  sulfonebenzo(b)thiophene 1,1-dioxide 6-Methylbenzothiophene 6-methyl-1-1.20E+05 4071.70*  471.23^(#) 111.26^(#) 39.85^(# )  18.52 benzo(b)thiophene 2,6- 2,6-dimethyl-1- 88.00 13.06*   3.96*   1.91*1.22* 0.93* Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 1967.00 248.62*   56.58^(#)  19.79^(#)  9.13 ^(C)  5.06^(C) Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide 2,6-2,6-dimethyl-1- 3.87E+05 10273.20* 1008.46^(# ) 213.25^(#) 70.66^(# ) 31.00^(# )  Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 313.00 35.58   9.09*   3.90* 2.28* 1.63*Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide 2,3,6-2,3,6-trimethyl-1- 5917.00 591.69  115.79^(#)  36.68^(#) 15.79 ^(C ) 8.32 ^(C) Trimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,3,6- 2,3,6-trimethyl-1- 1.17E+06 2.51E+04 2141.44^(# ) 412.38^(#)127.96^(# )  53.49^(# )  Trimethylbenzothiophene benzo(b)thiopheneDibenzothiophene dibenzothiophene 251.00 25.17   6.16*   2.60* 1.51*1.07* oxide 5-oxide Dibenzothiophene dibenzothiophene 6267.00 472.09  80.07^(#)  23.20^(#)  9.39 ^(C)  4.73 ^(C) sulfone 5,5-dioxideDibenzothiophene dibenzothiophene 6.67E+05 1.20E+04  959.31^(#)178.5^(#)  54.28^(# )  22.40^(# )  4-Methyldibenzothiophene4-methyldibenzothiophene 718.00 56.44  11.74*   4.43* 2.37* 1.57* oxide5-oxide 4-Methyldibenzothiophene 4-methyldibenzothiophene 1.79E+041060.44  155.12^(#)  40.89^(#) 15.51 ^(C )  7.46 ^(C) sulfone5,5-dioxide 4-Methyldibenzothiophene 4-methyldibenzothiophene 1.84E+062.72E+04 1896.52  322.84^(#) 92.18^(# )  36.31^(# )  3,6- 3,6- 1664.0096.24  17.31   5.96* 3.00* 1.93* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 3,6- 3,6- 4.41E+04 1977.55 259.57 63.67^(#) 22.97^(# )  10.64 ^(C ) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 3,6- 3,6- 5.81E+06 6.88E+044062.65  618.10^(#) 163.05^(# )  60.56^(# )  Dimethyldibenzothiophenedimethyldibenzothiophene 4,6- 4,6- 2468.00 104.82  18.87   6.48* 3.26*2.08* Dimethyldibenzothiophene dimethyldibenzothiophene oxide 5-oxide4,6- 4,6- 3.74E+04 2182.14 281.61  68.24^(#) 24.40^(# )  11.23 ^(C )Dimethyldibenzothiophene dimethyldibenzothiophene sulfone 5,5-dioxide4,6- 4,6- 5.04E+06 6.75E+04 4015.90  613.49^(#) 162.24^(# )  60.36^(# ) Dimethyldibenzothiophene dimethyldibenzothiophene 2,4- 2,4- 1542.00148.80  26.01   8.69* 4.24* 2.63* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 2,4- 2,4- 3.90E+04 1968.12 267.19 67.31^(#) 24.80^(# )  11.69 ^(C ) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 2,4- 2,4- 6.02E+06 6.13E+043762.60  587.60^(#) 157.89^(# )  59.46^(# )  Dimethyldibenzothiophenedimethyldibenzothiophene 2,4,7- 2,4,7- 4095.00 204.56  31.72   9.90*4.66* 2.84* Trimethyldibenzothiophene trimethyldibenzothiophene oxide5-oxide 2,4,7- 2,4,7- 9.72E+04 4114.13 477.44 107.82^(#) 36.70^(# ) 16.29 ^(C ) Trimethyldibenzothiophene trimethyldibenzothiophene sulfone5,5-dioxide 2,4,7- 2,4,7- 2.05E+07 1.82E+05 9081.97  1236.03^(#) 301.37^(# )  105.61^(# )  Trimethyldibenzothiophenetrimethyldibenzothiophene 4-Ethyldibenzothiophene4-ethyldibenzothiophene 1706.00 106.31  19.14   6.59* 3.31* 2.11* oxide5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene 5.43E+04 2379.14288.13  67.17^(#) 23.41^(# )  10.58 ^(C ) sulfone 5,5-dioxide4-Ethyldibenzothiophene 4-ethyldibenzothiophene 5.28E+06 6.19E+043733.25  577.43^(#) 154.25^(# )  57.86^(# )  4-Propyldibenzothiophene4-propyldibenzothiophene 4103.00 197.90  30.36   9.43* 4.42* 2.69* oxide5-oxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 1.60E+055353.77 543.31 112.57^(#) 36.10^(# )  15.34 ^(C ) sulfone 5,5-dioxide4-Propyldibenzothiophene 4-propyldibenzothiophene 1.72E+07 1.52E+057603.31  1040.43^(#)  254.96^(# )  89.74^(# )  2-Butyldibenzothiophene2-butyldibenzothiophene 1.43E+04 491.67  60.43   16.23* 6.90* 3.91 oxide 5-oxide 2-Butyldibenzothiophene 2-butyldibenzothiophene 3.38E+059483.96 845.18 159.73^(#) 47.89^(# )  19.34  sulfone 5,5-dioxide2-Butyldibenzothiophene 2-butyldibenzothiophene 7.58E+07 4.62E+051.82E+04 2114.09*  461.46^(# )  149.06   2-Pentyldibenzothiophene2-pentyldibenzothiophene 5.25E+04 1353.65 137.54  32.46 12.56*  6.62*oxide 5-oxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1.07E+062.27E+04 1683.13  281.50  77.44^(# )  29.35^(# )  sulfone 5,5-dioxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 2.67E+08 1.22E+063.99E+04 4096.46   819.52^(# )  248.23^(# )  1-Phenyldibenzothiophene1-Phenyldibenzothiophene 1.17E+04 346.79  40.02   10.38* 4.31* 2.40*oxide 5-oxide 1-Phenyldibenzothiophene 1-phenyldibenzothiophene 3.46E+057700.99 613.74 108.62^(#) 31.20^(# )  12.23 ^(C ) sulfone 5,5-dioxide1-Phenyldibenzothiophene 1-phenyldibenzothiophene 4.77E+07 2.47E+059114.87  1026.24^(#)  219.98^(# )  70.27  4-Phenyldibenzothiophene4-phenyldibenzothiophene 6.25E+04 1308.50 119.33  25.85 9.26* 4.54*oxide 5-oxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 3.59E+057511.03 578.80 100.47  28.52^(# )  11.09 ^(C ) sulfone 5,5-dioxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 5.26E+07 2.51E+058771.03  949.21  197.54   61.68  Dodecane Dodecane 6.02E+08 8.57E+065.46E+05 8.65E+04 2.34E+04 8817.80   Naphthalene bicyclo[4.4.0]deca-5.55E+04 2395.70 324.00  84.70 32.60  15.90  1,3,5,7,9-pentene Dibutylsulfoxide 1-butylsulfinyl-butane 49.90 8.50*   2.80*   1.50* 1.00* 0.80*Dibutyl sulfone 1-butylsulfonyl-butane 324.80 81.70^(#)   28.50^(#) 13.50 ^(C)  7.90 ^(C)  5.30 ^(C) Dibutyl sulfide 1-butylsulfanyl-butane5.23E+05  2.50E+04^(#) 3243.50^(# ) 804.00^(#) 294.70^(# )  138.60^(# ) Thiophene sulfide tetrahydrothiophene 2.00 1.10*   0.70*   0.60 0.50 0.50  1-oxide Thiophene sulfone tetrahydrothiophene 43.10 16.00^(#)    7.30 ^(C)   4.00 2.60  1.80  1,1-dioxide Thiophene Thiophene 1819.20187.00^(#)   43.60^(#)  16.40 8.10  4.80  Toluene Methylbenzene 1.26E+041029.20 204.20  68.60 31.40  17.50  Solvent (Acetonitrile W %/Water W %)Compound 60/40 70/30 80/20 90/10 100/0 Common Name IUPAC ActivityCoefficient 6-Methylbenzothiophene 6-methyl-1- 0.72  0.69 0.71 0.80 1.06oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1- 2.42 1.70 1.28 1.01 0.84 sulfone benzo(b)thiophene 1,1-dioxide6-Methylbenzothiophene 6-methyl-1- 10.22  6.36 4.31 3.11 2.36benzo(b)thiophene 2,6- 2,6-dimethyl-1- 0.80  0.76 0.79 0.90 1.26Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 3.18  2.20 1.62 1.27 1.05 Dimethylbenzothiophenebenzo(b)thiophene sulfone 1,1-dioxide 2,6- 2,6-dimethyl-1- 16.37  9.846.48 4.57 3.39 Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 1.33* 1.20 1.19 1.31 1.76 Trimethylbenzothiophene-benzo(b)thiophene oxide 1-oxide 2,3,6- 2,3,6-trimethyl-1-  5.04 ^(C)3.37 2.43 1.86 1.50 Trimethylbenzothiophene benzo(b)thiophene sulfone1,1-dioxide 2,3,6- 2,3,6-trimethyl-1- 27.23^(# )  15.89  10.23  7.075.16 Trimethylbenzothiophene benzo(b)thiophene Dibenzothiophenedibenzothiophene 0.87  0.79 0.77 0.84 1.08 oxide 5-oxideDibenzothiophene dibenzothiophene 2.77  1.81 1.28 0.96 0.77 sulfone5,5-dioxide Dibenzothiophene dibenzothiophene 11.30  6.55 4.20 2.90 2.114-Methyldibenzothiophene 4-methyldibenzothiophene 1.22* 1.05 1.00 1.051.32 oxide 5-oxide 4-Methyldibenzothiophene 4-methyldibenzothiophene 4.21 ^(C) 2.67 1.84 1.36 1.07 sulfone 5,5-dioxide4-Methyldibenzothiophene 4-methyldibenzothiophene 17.6^(# )  9.97 6.244.23 3.03 3,6- 3,6- 1.45* 1.24 1.17 1.25 1.64 Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 3,6- 3,6-  5.85 ^(C) 3.63 2.461.79 1.38 Dimethyldibenzothiophene dimethyldibenzothiophene sulfone5,5-dioxide 3,6- 3,6- 28.20^(# )  15.34  9.33 6.17 4.33Dimethyldibenzothiophene dimethyldibenzothiophene 4,6- 4,6- 1.56* 1.321.23 1.29 1.66 Dimethyldibenzothiophene dimethyldibenzothiophene oxide5-oxide 4,6- 4,6-  6.13 ^(C) 3.79 2.56 1.85 1.43Dimethyldibenzothiophene dimethyldibenzothiophene sulfone 5,5-dioxide4,6- 4,6- 28.13^(# )  15.32  9.33 6.17 4.33 Dimethyldibenzothiophenedimethyldibenzothiophene 2,4- 2,4- 1.92* 1.58 1.43 1.45 1.77Dimethyldibenzothiophene dimethyldibenzothiophene oxide 5-oxide 2,4-2,4-  6.51 ^(C) 4.08 2.79 2.05 1.59 Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 2,4- 2,4- 27.98^(# ) 15.35  9.40 6.25 4.41 Dimethyldibenzothiophene dimethyldibenzothiophene2,4,7- 2,4,7- 2.07*  1.72* 1.59 1.66 2.17 Trimethyldibenzothiophenetrimethyldibenzothiophene oxide 5-oxide 2,4,7- 2,4,7-  8.66 ^(C)  5.23^(C) 3.47 2.48 1.89 Trimethyldibenzothiophene trimethyldibenzothiophenesulfone 5,5-dioxide 2,4,7- 2,4,7- 47.01^(# )  24.69* 14.59  9.41 6.47Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 1.58* 1.33 1.24 1.281.60 oxide 5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene  5.70^(C) 3.48 2.33 1.68 1.29 sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 27.15^(# )  14.87  9.10 6.04 4.264-Propyldibenzothiophene 4-propyldibenzothiophene 1.95*  1.61* 1.48 1.521.93 oxide 5-oxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 7.89 ^(C)  4.64 ^(C) 3.02 2.12 1.59 sulfone 5,5-dioxide4-Propyldibenzothiophene 4-propyldibenzothiophene 40.11^(# )  21.14^(# )12.53  8.11 5.59 2-Butyldibenzothiophene 2-butyldibenzothiophene 2.70* 2.15*  1.92* 1.95 2.45 oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene  9.56 ^(C)  5.45 ^(C)  3.46 ^(C) 2.38 1.76sulfone 5,5-dioxide 2-Butyldibenzothiophene 2-butyldibenzothiophene62.35^(# )  31.19^(# ) 17.72^(# ) 11.06  7.40 2-Pentyldibenzothiophene2-pentyldibenzothiophene 4.31*  3.26*  2.80* 2.71 3.23 oxide 5-oxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 13.82 ^(C )  7.59 ^(C) 4.67 ^(C) 3.13 2.27 sulfone 5,5-dioxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 98.85^(# )  47.55^(# ) 26.18^(# ) 15.92  10.42 1-Phenyldibenzothiophene 1-Phenyldibenzothiophene 1.63* 1.28 1.13 1.131.39 oxide 5-oxide 1-Phenyldibenzothiophene 1-phenyldibenzothiophene 5.91 ^(C) 3.32 2.07 1.41 1.03 sulfone 5,5-dioxide1-Phenyldibenzothiophene 1-phenyldibenzothiophene 29.19  14.53  8.235.13 3.44 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 2.74* 1.931.53 1.36 1.42 oxide 5-oxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene  5.33 ^(C) 2.98 1.86 1.26 0.92 sulfone5,5-dioxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 25.16 12.34  6.91 4.26 2.83 Dodecane Dodecane 4151.50   2277.40   1393.70  923.70  647.10  Naphthalene bicyclo[4.4.0]deca- 9.20  5.90 4.10 3.002.30 1,3,5,7,9-pentene Dibutyl sulfoxide 1-butylsulfinyl-butane 0.80* 0.80*  1.00*  1.40*  2.80* Dibutyl sulfone 1-butylsulfonyl-butane  3.90^(C)  3.10 ^(C)  2.50 ^(C)  2.20 ^(C)  2.10 ^(C) Dibutyl sulfide1-butylsulfanyl-butane 77.00^(# )  48.10^(# ) 32.70^(# ) 23.70^(# )18.00^(# ) Thiophene sulfide tetrahydrothiophene 0.50  0.60 0.70 0.801.10 1-oxide Thiophene sulfone tetrahydrothiophene 1.40  1.10 0.90 0.800.70 1,1-dioxide Thiophene Thiophene 3.20  2.30 1.70 1.40 1.10 TolueneMethylbenzene 11.00  7.70 5.70 4.40 3.50

Acetic Acid Formulations

In a further embodiment of the present invention, the solventformulation comprises an aqueous solution of acetic acid. An aqueoussolution of acetic acid having a concentration of about 2.5 W % to about60 W % is particularly useful as a selective solvent formulation forextraction of sulfoxide products, and an aqueous solution of acetic acidhaving a concentration of about 30 W % to about 70 W % is particularlyuseful for extraction of a sulfoxidation products, i.e., sulfoxides andsulfones. The level of extraction and the specific concentration of theselective solvent formulation depend on factors including, but notlimited to the sulfur speciation of the feed hydrocarbon mixture andwhether the target sulfoxide products or sulfoxidation products to beextracted are non-bulky or bulky. For non-bulky sulfoxide products, theconcentration of the aqueous acetic acid solution can be about 2.5 W %to about 20 W %, which will extract the non-bulky sulfoxide products,while minimizing co-extraction of certain sulfones, untreatedorganosulfur compounds, non-heteroatom aromatics and other hydrocarbons.For bulky sulfoxide products and/or bulky sulfoxidation products, theconcentration of the aqueous acetic acid solution can be about 30 W % toabout 70 W %, which will extract the bulky sulfoxide and/orsulfoxidation products, while minimizing co-extraction of non-heteroatomaromatics, untreated organosulfur compounds and other hydrocarbons.

In an extractive simulation, COSMO-RS software was used to simulate γfor selective extraction of oxidized model A fuel by solventformulations of aqueous acetic acid. Acetic acid is desirable as a polarorganic solvent due to its relatively low boiling point, therebyfacilitating recovery and separation from the sulfoxide products or thesulfoxidation products.

Table 5A illustrates the activity coefficient of differentconcentrations of aqueous acetic acid. Based on the activity coefficientvalues in Table 5A, a useful aqueous acetic acid selective solventformulation has a concentration of about 20 W % to about 40 W % forextraction of DBT sulfoxide, with minimal co-extraction of certainsulfones, untreated organosulfur compounds, aromatics and otherhydrocarbons, as shown in FIG. 12. It is also apparent from FIG. 12 andthe data in Table 5A that a useful concentration of acetic acid is about40 W % to about 60 W % for extraction of DBT sulfoxide combined with DBTsulfone, with minimal co-extraction of aromatics, certain untreatedorganosulfur compounds and other hydrocarbons. A concentration of aceticacid of about 40 W % to about 50 W % is also suitable for extraction ofthiophene sulfoxide, thiophene sulfone, dibutyl sulfoxide and dibutylsulfone. If the target sulfoxidation products are primarily thiophenesulfoxide and dibutyl sulfoxide, a useful selective solvent formulationwill have about 5 W % to about 20 W % aqueous acetic acid, as shown inFIGS. 13 and 14. These extractions occur selectively with minimumco-extraction of other hydrocarbon constituents such as dodecane (nC₁₂),toluene, naphthalene, thiophene, dibenzothiophene and dibutyl sulfides.

In another extraction simulation, COSMO-RS software was used to simulateγ for formulations of aqueous acetic acid as extraction solvents foroxidized model B fuel. Activity coefficient values as shown in Table 5Bindicate that certain formulations of aqueous acetic acid willselectively extract bulky sulfoxide products while minimizingco-extraction of their corresponding sulfones and underlyingorganosulfur compounds. In addition, activity coefficient values asshown in Table 5B indicate that certain formulations of aqueousacetonitrile will selectively extract bulky sulfoxidation products,including sulfoxides and sulfones, with minimal co-extraction ofaromatics, untreated organosulfur compounds and other hydrocarbons.Based on the activity coefficient values in Table 5B, a useful aceticacid selective solvent formulation has a concentration of about 20 W %to about 70 W % for selective extraction of bulky sulfoxidation productsincluding alkyl and dialkyl derivatives of benzothiophenes anddibenzothiophenes. In addition, aqueous acetic acid selective solventformulations of about 10 W % to about 50 W % are also useful forextraction of bulky sulfoxide products including with minimalco-extraction of certain sulfones, aromatics, untreated organosulfurcompounds and other hydrocarbons.

Furthermore, Table 5B and FIGS. 15-17 show the efficacy of the selectivesolvent formulation, particularly in the range of about 30 W % to about70 W % aqueous acetic acid, for selective extraction of bulkysulfoxidation products including sulfoxides and sulfones of thiophenesand various alkylated thiophenes.

In Table 5B, activity coefficients for targeted sulfoxides for whichextraction is favored are marked with an asterisk (“*”), activitycoefficients for non-targeted underlying organosulfur compounds and incertain cases corresponding sulfones for which co-extraction isminimized are marked with a pound symbol (“#”). Furthermore, activitycoefficients for targeted sulfones for which extraction is favored(i.e., in combination with corresponding sulfoxides) are marked with aletter “C”.

It is noted that although the activity coefficient values for certainhigh concentration acetic acid formulations indicate favorableextraction of certain bulky or non-bulky sulfoxidation products(including sulfoxides and sulfones), these high concentration aceticacid formulations (e.g., greater than 70 W %) also extract untargetedspecies and therefore are not particularly desirable for extraction of abroad array of organosulfur oxidation products.

TABLE 5A Solvent (Acetic Acid W %/Water W %) 0/100 10/90 20/80 30/7040/60 50/50 60/40 70/30 80/20 90/10 100/0 Compound Activity Coefficientdibenzothiophene 5-oxide 321.00 16.40 3.25 1.15 0.54 0.30 0.18 0.12 0.080.06 0.04 (DBT sulfoxide) dibenzothiophene 5,5-dioxide 6063.00 416.0092.80 35.20 17.60 10.70 7.24 5.37 4.18 3.39 2.86 (DBT sulfone)dibenzothiophene (DBT) 7.90E+05 1.45E+04 1541.00 365.00 133.00 63.4035.90 22.90 16.00 11.80 9.21 1-butylsulfinyl-butane 51.40 2.69 0.52 0.170.08 0.04 0.02 0.01 0.01 0.01 0.00 (Dibutyl Sulfoxide) 1-butylsulfony1-butane 337.00 37.30 11.00 5.05 2.89 1.90 1.35 1.02 0.80 0.65 0.54(Dibutyl Sulfone) 1-butylsulfany 1-butane 5.04E+05 1.31E+04 1652.00433.00 169.00 83.90 48.90 31.80 22.60 16.90 13.20 (Dibutyl Sulfide)Thiophene Sulfoxide 2.83 0.77 0.38 0.24 0.17 0.13 0.10 0.08 0.06 0.050.04 Thiophene Sulfone 49.40 18.20 10.20 6.82 5.16 4.18 3.56 3.13 2.802.56 2.36 Thiophene 2208.00 213.00 56.80 24.00 13.20 8.41 5.99 4.53 3.603.00 2.56 Naphthalene 4.44E+04 2186.00 392.00 126.00 57.40 31.80 20.3014.10 10.60 8.33 6.82 Toluene 9799.00 812.00 192.00 75.20 38.90 23.6016.10 11.90 9.30 7.61 6.42 nC₁₂ 3.52E+08 3.14E+06 2.18E+05 3.89E+041.16E+04 4770.00 2392.00 1394.00 898.00 626.00 464.00

TABLE 5B Solvent (Acetic Acid W %/Water W %) Compound 0/100 10/90 20/8030/70 40/60 50/50 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1- 47.00 3.88* 1.02* 0.43* 0.23*   0.14*oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-988.00 111.41^(#) 33.42^(# )  15.36 ^(C )  8.92 ^(C)  5.98 ^(C) sulfonebenzo(b)thiophene 1.1-dioxide 6-Methylbenzothiophene 6-methyl-1-1.20E+05 3753.75^(#) 545.27^(# )  159.53^(# )  67.98^(# )  36.43^(#)benzo(b)thiophene 2,6- 2,6-dimethyl-1- 88.00 5.22* 1.15* 0.43* 0.21*  0.12* Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1- 1967.00 165.47^(#) 42.91^(# )  18.08^(# )   9.91 ^(C) 6.37 ^(C) Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,6- 2,6-dimethyl-1- 3.87E+05 8718.11^(#) 1060.17^(#  )   277.85^(# ) 109.85^(# )  55.80^(#) Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 313.00 13.49* 2.52* 0.86* 0.39*   0.21*Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide 2,3,6-2,3,6-trimethyl-1- 5917.00 362.34^(#) 79.34^(# )  30.11^(# )  15.37^(C )  9.38 ^(C) Trimethylbenzothiophene benzo(b)thiophene sulfone1,1-dioxide 2,3,6- 2,3,6-trimethyl-1- 1.17E+06  1.98E+04^(#)2068.98^(#  )   493.69^(# )  183.21^(# )  88.94^(#)Trimethylbenzothiophene benzo(b)thiophene Dibenzothiophenedibenzothiophene 251.00 12.00* 2.37* 0.83* 0.39*   0.22* oxide 5-oxideDibenzothiophene dibenzothiophene 6267.00 390.07^(#) 85.32^(# ) 32.30^(# )  16.46^(# )   10.05 ^(C) sulfone 5.5-dioxide Dibenzothiophenedibenzothiophene 6.67E+05  1.20E+04^(#) 1294.98^(#  )   315.39^(# ) 118.72^(# )  58.27^(#) 4-Methyldibenzothiophene 4-methyldibenzothiophene718.00 25.56 4.30* 1.38* 0.61*   0.32* oxide 5-oxide4-Methyldibenzothiophene 4-methyldibenzothiophene 1.79E+04 803.06147.88^(# )  50.35^(# )  23.87^(# )   13.84 ^(C) sulfone 5,5-dioxide4-Methyldibenzothiophene 4-methyldibenzothiophene 1.84E+06 2.51E+042336.12^(#  )   519.57^(# )  183.93^(# )  86.39^(#) 3,6- 3,6- 1664.0042.34 5.96* 1.70* 0.69*   0.35* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 3,6- 3,6- 4.41E+04 1460.32229.56^(# )  70.98^(# )  31.54^(# )  17.45^(#) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 3,6- 3,6- 5.81E+06 5.74E+044486.68^(#  )   895.55^(# )  294.51^(# )  131.18^(#) Dimethyldibenzothiophene dimethyldibenzothiophene 4,6- 4,6- 2468.0064.61 9.24* 2.67* 1.10*   0.56* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 4,6- 4,6- 3.74E+04 1317.07214.87^(# )  68.09^(# )  30.78^(# )  17.23^(#) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 4,6- 4,6- 5.04E+06 5.26E+044244.75^(#  )   864.88^(# )  288.56^(# )  129.90^(#) Dimethyldibenzothiophene dimethyldibenzothiophene 2,4- 2,4- 1542.0038.69 5.40* 1.53* 0.62*   0.31* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 2,4- 2,4- 3.90E+04 1315.83209.43^(# )  65.32^(# )  29.20^(# )  16.22^(#) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 2,4- 2,4- 6.02E+06 5.87E+044561.91^(#  )   907.53^(# )  297.80^(# )  132.45^(#) Dimethyldibenzothiophene dimethyldibenzothiophene 2,4,7- 2,4,7- 4095.0073.74 8.64* 2.20* 0.83*   0.39* Trimethyldibenzothiophenetrimethyldibenzothiophene oxide 5-oxide 2,4,7- 2,4,7- 9.72E+04 2405.49327.16^(# )  92.76^(# )  38.89^(# )  20.63^(#) Trimethyldibenzothiophenetrimethyldibenzothiophene sulfone 5,5-dioxide 2,4,7- 2,4,7- 2.05E+071.43E+05 9262.17^(#  )   1648.89^(#  )   501.70^(# )  211.35^(#) Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 1706.00 44.80 6.42*1.86* 0.77*   0.39* oxide 5-oxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.43E+04 1742.29 266.57^(# )  80.89^(# ) 35.46^(# )  19.43^(#) sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.28E+06 5.35E+04 4261.07^(#  )   861.29^(# ) 285.83^(# )  128.21^(#)  4-Propyldibenzothiophene4-propyldibenzothiophene 4103.00 77.28 9.25* 2.39* 0.91*   0.43* oxide5-oxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 1.60E+053664.87 467.12^(# )  126.57^(# )  51.37^(# )  26.63^(#) sulfone5,5-dioxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 1.72E+071.23E+05 8147.27^(#  )   1466.21^(#  )   449.52^(# )  190.48^(#) 2-Butyldibenzothiophene 2-butyldibenzothiophene 1.43E+04 171.12 15.99* 3.53* 1.21*   0.53* oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene 3.38E+05 5622.88 609.83^(# )  149.84^(# ) 56.93^(# )  28.15^(#) sulfone 5,5-dioxide 2-Butyldibenzothiophene2-butyldibenzothiophene 7.58E+07 3.50E+05 1.81E+04 2797.58^(#  )  771.74^(# )  302.98^(#)  2-Pentyldibenzothiophene2-pentyldibenzothiophene 5.25E+04 446.27 34.69  6.86* 2.17*   0.90*oxide 5-oxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1.07E+061.26E+04 1135.90   248.30^(# )  87.10^(# )  40.67^(#) sulfone5,5-dioxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 2.67E+088.69E+05 3.72E+04 5094.73^(#  )   1296.30^(#  )   480.22^(#) 1-Phenyldibenzothiophene 1-phenyldibenzothiophene 1.17E+04 153.04 15.05 3.44* 1.21*   0.54* oxide 5-oxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 3.46E+05 5816.08 633.65   156.05^(# ) 59.46^(# )  29.50^(#) sulfone 5,5-dioxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 4.77E+07 2.34E+05 1.26E+04 1995.65^(#  )  561.69^(# )  224.04^(#)  4-Phenyldibenzothiophene4-phenyldibenzothiophene 6.25E+04 701.76 62.52  13.49*  4.58*   2.02*oxide 5-oxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 3.59E+055992.57 641.92   155.98^(# )  58.82^(# )  28.95^(#) sulfone 5,5-dioxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 5.26E+07 2.47E+051.28E+04 1984.53^(#  )   548.22^(# )  215.60^(#)  Dodecane Dodecane6.02E+08 3.70E+06 2.27E+05 3.89E+04 1.16E+04 4772.90   Naphthalenebicyclo[4.4.0]deca- 5.55E+04 2371.10 403.00   129.10   58.60  32.80 1,3,5,7,9-pentene Dibutyl sulfoxide 1-butylsulfinyl-butane 49.90 2.30*0.43* 0.14* 0.06*   0.03* Dibutyl sulfone 1-butylsulfonyl-butane 324.8031.70^(#)  9.20 ^(C)  4.20 ^(C)  2.40 ^(C)  1.60 ^(C) Dibutyl sulfide1-butylsulfanyl-butane 5.23E+05  1.30E+04^(#) 1701.80^(#  )  464.30^(# )  188.70^(# )  97.50^(#) Thiophene sulfidetetrahydrothiophene 2.00 0.58* 0.29* 0.19* 0.13   0.10 1-oxide Thiophenesulfone tetrahydrothiophene 43.10 15.90^(#)  9.00 ^(C)  6.10 ^(C) 4.70  3.80 1,1-dioxide Thiophene Thiophene 1819.20 190.90^(#) 53.50^(# ) 23.50^(# )  13.20   8.70 Toluene Methylbenzene 1.26E+04 909.90 207.30  80.00  41.10  25.20  Solvent (Acetic Acid W %/Water W %) Compound 60/4070/30 80/20 90/10 100/0 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1-   0.09* 0.06   0.04 0.03 0.02 oxidebenzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-  4.40 ^(C)3.45   2.84 2.41 2.10 sulfone benzo(b)thiophene 1.1-dioxide6-Methylbenzothiophene 6-methyl-1- 22.65^(#) 15.57  11.51  8.97 7.27benzo(b)thiophene 2,6- 2,6-dimethyl-1-   0.07* 0.05*  0.03 0.02 0.02Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide 2,6-2,6-dimethyl-1-  4.54 ^(C)  3.48 ^(C)  2.80 2.34 2.01Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide 2,6-2,6-dimethyl-1- 33.31^(#) 22.20^(# )  16.00  12.22  9.74Dimethylbenzothiophene benzo(b)thiophene 2,3,6- 2,3,6-trimethyl-1-  0.13* 0.08*   0.06*  0.04* 0.03 Trimethylbenzothiophene-benzo(b)thiophene oxide 1-oxide 2,3,6- 2,3,6-trimethyl-1-  6.44 ^(C) 4.78 ^(C)  3.76 ^(C)  3.08 ^(C) 2.61 Trimethylbenzothiophenebenzo(b)thiophene sulfone 1,1-dioxide 2,3,6- 2,3,6-trimethyl-1-51.33^(#) 33.32^(# )  23.53^(#) 17.67^(# ) 13.89 Trimethylbenzothiophene benzo(b)thiophene Dibenzothiophenedibenzothiophene   0.13* 0.09*  0.06 0.04 0.03 oxide 5-oxideDibenzothiophene dibenzothiophene  6.91 ^(C)  5.15 ^(C)  4.06 3.34 2.84sulfone 5.5-dioxide Dibenzothiophene dibenzothiophene 33.92^(#)22.18^(# )  15.75  11.89  9.39 4-Methyldibenzothiophene4-methyldibenzothiophene   0.19* 0.12*   0.08* 0.06 0.04 oxide 5-oxide4-Methyldibenzothiophene 4-methyldibenzothiophene  9.15 ^(C)  6.61 ^(C) 5.09 ^(C) 4.11 3.43 sulfone 5,5-dioxide 4-Methyldibenzothiophene4-methyldibenzothiophene 48.66^(#) 31.02^(# )  21.59^(#) 16.03  12.49 3,6- 3,6-   0.19* 0.12*   0.08*  0.05* 0.04 Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 3,6- 3,6-  11.13 ^(C)  7.82 ^(C) 5.89 ^(C)  4.67 ^(C) 3.84 Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 3,6- 3,6- 71.01^(#)43.89^(# )  29.81^(#) 21.69^(# ) 16.63  Dimethyldibenzothiophenedimethyldibenzothiophene 4,6- 4,6-   0.32* 0.20*   0.13*  0.09* 0.07Dimethyldibenzothiophene dimethyldibenzothiophene oxide 5-oxide 4,6-4,6-  11.10 ^(C)  7.85 ^(C)  5.94 ^(C)  4.72 ^(C) 3.89Dimethyldibenzothiophene dimethyldibenzothiophene sulfone 5,5-dioxide4,6- 4,6- 70.89^(#) 44.10^(# )  30.10^(#) 22.00^(# ) 16.92 Dimethyldibenzothiophene dimethyldibenzothiophene 2,4- 2,4-   0.17*0.11*   0.07*  0.05*  0.03* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 2,4- 2,4-  10.39 ^(C)  7.32 ^(C) 5.52 ^(C)  4.38 ^(C)  3.60 ^(C) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 2,4- 2,4- 71.62^(#)44.23^(# )  30.02^(#) 21.83^(# ) 16.73^(# ) Dimethyldibenzothiophenedimethyldibenzothiophene 2,4,7- 2,4,7-   0.21* 0.12*   0.08*  0.05* 0.04* Trimethyldibenzothiophene trimethyldibenzothiophene oxide 5-oxide2,4,7- 2,4,7-  12.75 ^(C)  8.74 ^(C)  6.45 ^(C)  5.02 ^(C)  4.07 ^(C)Trimethyldibenzothiophene trimethyldibenzothiophene sulfone 5,5-dioxide2,4,7- 2,4,7- 109.72^(#)  65.64^(# )  43.45^(#) 30.96^(# ) 23.32^(# )Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene   0.22* 0.14*   0.09* 0.06*  0.04* oxide 5-oxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene  12.32 ^(C)  8.62 ^(C)  6.47 ^(C)  5.11 ^(C) 4.19 ^(C) sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 69.78^(#) 43.31^(# )  29.52^(#) 21.55^(# )16.56^(# ) 4-Propyldibenzothiophene 4-propyldibenzothiophene   0.24*0.14*   0.09*  0.06*  0.04* oxide 5-oxide 4-Propyldibenzothiophene4-propyldibenzothiophene 16.20^(#) 10.97 ^(C )  8.03 ^(C)  6.21 ^(C) 5.01 ^(C) sulfone 5,5-dioxide 4-Propyldibenzothiophene4-propyldibenzothiophene 99.34^(#) 59.66^(# )  39.61^(#) 28.30^(# )21.36^(# ) 2-Butyldibenzothiophene 2-butyldibenzothiophene   0.27* 0.15*  0.09*  0.06*  0.04* oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene 16.51^(#) 10.87 ^(C )  7.77 ^(C)  5.90 ^(C) 4.68 ^(C) sulfone 5,5-dioxide 2-Butyldibenzothiophene2-butyldibenzothiophene 149.17^(#)  85.65^(# )  54.86^(#) 38.07^(# )28.05^(# ) 2-Pentyldibenzothiophene 2-pentyldibenzothiophene   0.44*0.24*   0.15*  0.09*  0.06* oxide 5-oxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 22.85^(#) 14.55 ^(C )  10.13 ^(C)  7.53 ^(C) 5.87 ^(C) sulfone 5,5-dioxide 2-Pentyldibenzothiophene2-pentyldibenzothiophene 226.35^(#)  125.64^(# )  78.35^(#) 53.20^(# )38.49^(# ) 1-Phenyldibenzothiophene 1-phenyldibenzothiophene   0.28*0.16*   0.10*  0.07*  0.05* oxide 5-oxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 17.37^(#) 11.49 ^(C )  8.25 ^(C)  6.29 ^(C) 5.01 ^(C) sulfone 5,5-dioxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 111.74^(#)  64.86^(# )  41.93^(#) 29.33^(# )21.76^(# ) 4-Phenyldibenzothiophene 4-phenyldibenzothiophene   1.05*0.61*   0.39*  0.26*  0.18* oxide 5-oxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene 16.94^(#) 11.14 ^(C )  7.97 ^(C)  6.05 ^(C) 4.81 ^(C) sulfone 5,5-dioxide 4-Phenyldibenzothiophene4-phenyldibenzothiophene 106.36^(#)  61.21^(# )  39.29^(#) 27.33^(# )20.18^(# ) Dodecane Dodecane 2437.20   1437.60   939.70   662.20 493.80  Naphthalene bicyclo[4.4.0]deca- 21.10  14.90  11.20  8.90 7.301,3,5,7,9-pentene Dibutyl sulfoxide 1-butylsulfinyl-butane   0.02* 0.01*  0.01*  0.00*  0.00* Dibutyl sulfone 1-butylsulfonyl-butane  1.10 ^(C) 0.90 ^(C)  0.70 ^(C)  0.60 ^(C)  0.50 ^(C) Dibutyl sulfide1-butylsulfanyl-butane 58.80^(#) 39.50^(# )  28.50^(#) 21.80^(# )17.40^(# ) Thiophene sulfide tetrahydrothiophene  0.08 0.06   0.05 0.040.03 1-oxide Thiophene sulfone tetrahydrothiophene  3.20 2.90   2.602.40 2.20 1,1-dioxide Thiophene Thiophene  6.30 4.80   3.90 3.30 2.80Toluene Methylbenzene 17.30  12.90  10.10  8.30 7.00

Formic Acid Formulations

In yet another embodiment of the process described herein, the solventformulation comprises an aqueous solution of formic acid. An aqueoussolution of formic acid having a concentration of about 2.5 W % to about50 W % is particularly useful as a selective solvent formulation forextraction of sulfoxide products, and an aqueous solution of formic acidhaving a concentration of about 50 W % to about 70 W % is particularlysuitable for extraction of bulky sulfoxidation products, i.e.,sulfoxides and sulfones. The level of extraction and the specificconcentration of the selective solvent formulation depend on factorsincluding, but not limited to the sulfur speciation of the feedhydrocarbon mixture and whether the target sulfoxide products orsulfoxidation products to be extracted are non-bulky or bulky. Fornon-bulky sulfoxide products, the concentration of the aqueous formicacid solution can be about 2.5 W % to about 30 W %, which will extractthe non-bulky sulfoxidation products, while minimizing co-extraction ofcertain sulfones, untreated organosulfur compounds, non-heteroatomaromatics and other hydrocarbons. For bulky sulfoxide products and/orbulky sulfoxidation products, the concentration of the aqueous formicacid solution can be about 30 W % to about 70 W %, which will desirablyextract the bulky sulfoxide products and/or bulky sulfoxidationproducts, while minimizing co-extraction of non-heteroatom aromatics andother hydrocarbons.

In an extractive simulation, COSMO-RS software was used to simulate γfor selective extraction of oxidized model A fuel by solventformulations of aqueous formic acid. Formic acid is desirable as a polarorganic solvent due to its relatively low boiling point, thereby andseparation from the sulfoxide products or the sulfoxidation products.

Table 6A illustrates the activity coefficient of differentconcentrations of aqueous formic acid. Based on the activity coefficientvalues in Table 6A, a useful aqueous formic acid selective solventformulation has a concentration of about 30 W % to about 40 W % forextraction of DBT sulfoxide, with minimal co-extraction of certainsulfones, untreated organosulfur compounds, aromatics and otherhydrocarbons, as shown in FIG. 18. It is also apparent from FIG. 18 andthe data in Table 6A that a suitable concentration of formic acid isabout 50 W % to about 70 W % for extraction of DBT sulfoxide combinedwith DBT sulfone, with minimal co-extraction of aromatics and otherhydrocarbons. A concentration of formic acid of about 50 W % to about 70W % is also useful for extraction of thiophene sulfoxide, thiophenesulfone, dibutyl sulfoxide and dibutyl sulfone. If the targetsulfoxidation products are primarily non-bulky sulfoxidation productssuch as thiophene sulfoxide and dibutyl sulfoxide, a suitable selectivesolvent formulation will have about 5 W % to about 20 W % aqueous formicacid, as shown in FIGS. 19 and 20. Sulfones of thiophene and dibutyl canbe extracted using about 30 W % to about 40 W % aqueous formic acid.

In another extraction simulation, COSMO-RS software was used to simulateγ for formulations of aqueous formic acid as extraction solvents foroxidized model B fuel. The results are shown in Table 6B. Activitycoefficient values as shown in Table 6B indicate that certainformulations of aqueous formic acid will selectively extract bulkysulfoxide products while minimizing co-extraction of their correspondingsulfones and underlying organosulfur compounds. In addition, activitycoefficient values as shown in Table 6B indicate that certainformulations of aqueous formic acid will selectively extract bulkysulfoxidation products, including sulfoxides and sulfones, with minimalco-extraction of aromatics, untreated organosulfur compounds and otherhydrocarbons. Based on the activity coefficient values in Table 6B, auseful formic acid selective solvent formulation has a concentration ofabout 20 W % to about 60 W % for selective extraction of bulky sulfoxideproducts including alkyl and dialkyl derivatives of benzothiophenes anddibenzothiophenes. In addition, aqueous formic acid selective solventformulations of about 50 W % to about 70 W % are also useful forextraction of bulky sulfoxidation products including sulfoxides andsulfones with minimal co-extraction of aromatics, untreated organosulfurcompounds and other hydrocarbons.

In Table 6B, activity coefficients for targeted sulfoxides for whichextraction is favored are marked with an asterisk (“*”), activitycoefficients for non-targeted underlying organosulfur compounds and incertain cases corresponding sulfones for which co-extraction isminimized are marked with a pound symbol (“#”). Furthermore, activitycoefficients for targeted sulfones for which extraction is favored(i.e., in combination with corresponding sulfoxides) are marked with aletter “C”.

It is noted that although the activity coefficient values for certainhigh concentration formic acid formulations indicate favorableextraction of certain bulky or non-bulky sulfoxidation products(including sulfoxides and sulfones), these high concentration formicacid formulations (e.g., greater than 70 W %) also extract untargetedspecies and therefore are not particularly desirable for extraction of abroad array of organosulfur oxidation products.

TABLE 6A Solvent (Formic Acid W %/Water W %) 0/100 10/90 20/80 30/7040/60 50/50 60/40 70/30 80/20 90/10 100/0 Compound Activity Coefficientdibenzothiophene 321.00 20.10 3.29 0.87 0.30 0.12 0.05 0.03 0.01 0.010.00 5-oxide (DBT sulfoxide) dibenzothiophene 6063.00 550.00 116.0038.50 17.00 8.94 5.37 3.56 2.51 1.86 1.43 5,5-dioxide (DBT sulfone)dibenzothiophene 7.90E+05 3.03E+04 3866.00 925.00 327.01 147.00 79.0048.40 32.10 22.90 17.30 (DBT) 1-butylsulfinyl- 51.40 4.35 0.79 0.21 0.070.03 0.01 0.00 0.00 0.00 0.00 butane (Di- butyl Sulfoxide)1-butylsulfonyl- 337.00 53.50 14.90 5.75 2.72 1.45 0.83 0.51 0.33 0.220.15 butane (Di- butyl Sulfone) 1-butylsulfanyl- 5.04E+05 3.60E+046248.00 1808.00 706.00 344.00 192.00 120.00 81.40 58.00 43.80 butane(Di- butyl Sulfide) Thiophene 2.83 0.63 0.23 0.11 0.06 0.03 0.02 0.010.01 0.00 0.00 Sulfoxide Thiophene 49.40 15.80 7.39 4.35 2.89 2.10 1.621.30 1.06 0.90 0.77 Sulfone Thiophene 2208.00 299.00 84.80 35.50 18.8011.50 7.85 5.75 4.48 3.63 3.03 Naphthalene 4.44E+04 4447.00 992.00340.00 156.00 84.80 53.00 36.20 26.60 20.50 16.40 Toluene 9799.001541.00 455.00 191.00 99.50 60.30 40.80 29.70 22.90 18.40 15.30 nC₁₂3.52E+08 2.02E+07 2.93E+06 7.29E+05 2.58E+05 1.16E+05 6.11E+04 3.63E+042.39E+04 1.68E+04 1.23E+04

TABLE 6B Solvent (Formic Acid W %/Water W %) Compound 0/100 10/90 20/8030/70 40/60 50/50 Common Name IUPAC Activity Coefficient6-Methylbenzothiophene 6-methyl-1- 47.00   4.66* 1.00* 0.31* 0.12* 0.05*oxide benzo(b)thiophene 1-oxide 6-Methylbenzothiophene 6-methyl-1-988.00   137.92^(#) 37.53^(# )  14.86 ^(C )  7.42 ^(C)  4.33 ^(C)sulfone benzo(b)thiophene 1,1-dioxide 6-Methylbenzothiophene 6-methyl-1-1.20E+05  7996.47^(#) 1404.85^(#  )   420.07^(# )  173.74^(# ) 89.09^(# )  benzo(b)thiophene 2,6- 2,6-dimethyl-1- 88.00   6.96* 1.27*0.35* 0.12* 0.05* Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide2,6- 2,6-dimethyl-1- 1967.00   224.00^(#) 53.33^(# )  19.19^(# )   8.91^(C)  4.90 ^(C) Dimethylbenzothiophene benzo(b)thiophene sulfone1,1-dioxide 2,6- 2,6-dimethyl-1- 3.87E+05  2.10E+04^(#) 3214.43^(#  )  871.68^(# )  335.39^(# )  162.83^(# )  Dimethylbenzothiophenebenzo(b)thiophene 2,3,6- 2,3,6-trimethyl-1- 313.00  20.72 3.38* 0.87*0.29* 0.12* Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide2,3,6- 2,3,6-trimethyl-1- 5917.00  560.48 118.20^(# )  39.07^(# ) 17.04^(# )   8.95 ^(C) Trimethylbenzothiophene benzo(b)thiophene sulfone1,1-dioxide 2,3,6- 2,3,6-trimethyl-1- 1.17E+06 5.34E+04 7260.63^(#  )  1812.20^(#  )   655.91^(# )  304.08^(# )  Trimethylbenzothiophenebenzo(b)thiophene Dibenzothiophene dibenzothiophene 251.00   16.05*2.61* 0.68* 0.23* 0.09* oxide 5-oxide Dibenzothiophene dibenzothiophene6267.00   558.13^(#) 115.43^(# )  38.08^(# )  16.73^(# )   8.89 ^(C)sulfone 5,5-dioxide Dibenzothiophene dibenzothiophene 6.67E+05 2.90E+04^(#) 3898.94^(#  )   975.20^(# )  355.37^(# )  165.95^(# ) 4-Methyldibenzothiophene 4-methyldibenzothiophene 718.00  38.85 5.66*1.37* 0.44* 0.17* oxide 5-oxide 4-Methyldibenzothiophene4-methyldibenzothiophene 1.79E+04 1321.69 241.96^(# )  73.25^(# ) 30.20^(# )  15.30 ^(C ) sulfone 5,5-dioxide 4-Methyldibenzothiophene4-methyldibenzothiophene 1.84E+06 6.73E+04 8077.23^(#  )  1862.05^(#  )   638.81^(# )  285.02^(# )  3,6- 3,6- 1664.00  65.78 8.16*1.75* 0.51* 0.18* Dimethyldibenzothiophene dimethyldibenzothiopheneoxide 5-oxide 3,6- 3,6- 4.41E+04 2372.72 381.46^(# )  105.25^(# ) 40.44^(# )  19.38^(# )  Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 3,6- 3,6- 5.81E+06 1.78E+05 1.86E+04^(#) 3874.72^(#  )   1235.12^(#  )   521.29^(# ) Dimethyldibenzothiophene dimethyldibenzothiophene 4,6- 4,6- 2468.00 72.03 9.03* 1.96* 0.58* 0.21* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 4,6- 4,6- 3.74E+04 2657.10424.30^(# )  116.55^(# )  44.66^(# )  21.38^(# ) Dimethyldibenzothiophene dimethyldibenzothiophene sulfone 5,5-dioxide4,6- 4,6- 5.04E+06 1.73E+05  1.80E+04^(#) 3771.02^(#  )  1203.06^(#  )   508.06^(# )  Dimethyldibenzothiophenedimethyldibenzothiophene 2,4- 2,4- 1542.00  112.92 14.77*  3.33* 1.03*0.38* Dimethyldibenzothiophene dimethyldibenzothiophene oxide 5-oxide2,4- 2,4- 3.90E+04 2412.31 403.33^(# )  114.42^(# )  44.88^(# ) 21.86^(# )  Dimethyldibenzothiophene dimethyldibenzothiophene sulfone5,5-dioxide 2,4- 2,4- 6.02E+06 1.56E+05  1.68E+04^(#) 3584.22^(#  )  1160.45^(#  )   495.62^(# )  Dimethyldibenzothiophenedimethyldibenzothiophene 2,4,7- 2,4,7- 4095.00  140.32 15.05*  2.92*0.79* 0.26* Trimethyldibenzothiophene trimethyldibenzothiophene oxide5-oxide 2,4,7- 2,4,7- 9.72E+04 4760.04 664.33^(# )  165.77^(# ) 59.04^(# )  26.66^(# )  Trimethyldibenzothiophenetrimethyldibenzothiophene sulfone 5,5-dioxide 2,4,7- 2,4,7- 2.05E+074.87E+05  4.40E+04^(#) 8297.46^(#  )   2455.13^(#  )   979.44^(# ) Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 1706.00  76.65 9.88*2.19* 0.66* 0.24* oxide 5-oxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.43E+04 3318.88 535.45^(# )  148.47^(# ) 57.46^(# )  27.79^(# )  sulfone 5,5-dioxide 4-Ethyldibenzothiophene4-ethyldibenzothiophene 5.28E+06 1.63E+05  1.74E+04^(#) 3715.68^(#  )  1202.49^(#  )   513.46^(# )  4-Propyldibenzothiophene4-propyldibenzothiophene 4103.00  149.01 16.62  3.32* 0.92* 0.32* oxide5-oxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 1.60E+057954.43 1116.39   280.50^(# )  100.92^(# )  46.18^(# )  sulfone5,5-dioxide 4-Propyldibenzothiophene 4-propyldibenzothiophene 1.72E+074.27E+05 3.96E+04 7627.44^(#  )   2291.23^(#  )   924.80^(# ) 2-Butyldibenzothiophene 2-butyldibenzothiophene 1.43E+04  380.74 34.47 5.92* 1.46* 0.46* oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene 3.38E+05 1.31E+04 1552.18   345.81^(# ) 113.43^(# )  48.19^(# )  sulfone 5,5-dioxide 2-Butyldibenzothiophene2-butyldibenzothiophene 7.58E+07 1.42E+06 1.09E+05 1.83E+04^(#)4987.54^(#  )   1867.14^(#  )   2-Pentyldibenzothiophene2-pentyldibenzothiophene 5.25E+04 1139.55 90.23  14.14*  3.28* 0.97*oxide 5-oxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1.07E+063.36E+04 3462.04   697.84^(# )  212.60^(# )  85.42^(# )  sulfone5,5-dioxide 2-Pentyldibenzothiophene 2-pentyldibenzothiophene 2.67E+084.03E+06 2.68E+05 4.08E+04^(#)  1.03E+04^(#) 3644.60^(#  )  1-Phenyldibenzothiophene 1-phenyldibenzothiophene 1.17E+04  289.1225.56  4.37* 1.09* 0.34* oxide 5-oxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 3.46E+05 1.18E+04 1334.18   289.97^(# ) 94.21^(# )  39.97^(# )  sulfone 5,5-dioxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 4.77E+07 8.08E+05 5.97E+04 9896.86^(#  )  2679.68^(#  )   1002.89^(#  )   4-Phenyldibenzothiophene4-phenyldibenzothiophene 6.25E+04 1472.81 127.96   22.10  5.68* 1.88*oxide 5-oxide 4-Phenyldibenzothiophene 4-phenyldibenzothiophene 3.59E+051.22E+04 1364.82   295.10   95.56^(# )  40.45^(# )  sulfone 5,5-dioxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 5.26E+07 8.50E+056.06E+04 9785.16   2597.17^(#  )   957.22^(# )  Dodecane Dodecane6.02E+08 2.50E+07 2.99E+06 6.61E+05 2.16E+05 9.21E+04 Naphthalenebicyclo[4.4.0]deca- 5.55E+04 5137.60 1085.50   365.60   164.40   89.70 1,3,5,7,9-pentene Dibutyl sulfoxide 1-butylsulfinyl-butane 49.90   3.80*0.60* 0.16* 0.05* 0.02* Dibutyl sulfone 1-butylsulfonyl-butane 324.80  44.30^(#) 11.30 ^(C )  4.10 ^(C)  1.80 ^(C)  0.90 ^(C) Dibutyl sulfide1-butylsulfanyl-butane 5.23E+05  3.73E+04^(#) 6457.00^(#  )  1854.50^(#  )   732.00^(# )  358.00^(# )  Thiophene sulfidetetrahydrothiophene 2.00*   0.50* 0.19* 0.09* 0.05* 0.03  1-oxideThiophene sulfone tetrahydrothiophene 43.10^(#)     14.40 ^(C)  6.90^(C)  4.10 ^(C)  2.70 ^(C) 2.00  1,1-dioxide Thiophene Thiophene1819.20^(#)   292.10^(#) 90.50^(# )  40.10^(# )  22.10^(# )  14.00 Toluene Methylbenzene 1.26E+04 1811.50 505.50   205.70   105.90   63.80 Solvent (Formic Acid W %/Water W %) Compound 60/40 70/30 80/20 90/10100/0 Common Name IUPAC Activity Coefficient 6-Methylbenzothiophene6-methyl-1- 0.03* 0.01* 0.01* 0.00* 0.00  oxide benzo(b)thiophene1-oxide 6-Methylbenzothiophene 6-methyl-1-  2.81 ^(C)  1.97 ^(C)  1.45^(C)  1.11 ^(C) 0.89  sulfone benzo(b)thiophene 1,1-dioxide6-Methylbenzothiophene 6-methyl-1- 52.96^(# )  34.95^(# )  24.90^(# ) 18.76^(# )  14.79  benzo(b)thiophene 2,6- 2,6-dimethyl-1- 0.02* 0.01*0.01* 0.00* 0.00* Dimethylbenzothiophene benzo(b)thiophene oxide 1-oxide2,6- 2,6-dimethyl-1-  3.03 ^(C)  2.03 ^(C)  1.45 ^(C)  1.07 ^(C)  0.83^(C) Dimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide 2,6-2,6-dimethyl-1- 92.76^(# )  59.17^(# )  41.02^(# )  30.20^(# ) 23.37^(# )  Dimethylbenzothiophene benzo(b)thiophene 2,3,6-2,3,6-trimethyl-1- 0.05* 0.02* 0.01* 0.01* 0.00*Trimethylbenzothiophene- benzo(b)thiophene oxide 1-oxide 2,3,6-2,3,6-trimethyl-1-  5.35 ^(C)  3.49 ^(C)  2.43 ^(C)  1.78 ^(C)  1.36^(C) Trimethylbenzothiophene benzo(b)thiophene sulfone 1,1-dioxide2,3,6- 2,3,6-trimethyl-1- 167.16^(# )  103.64^(# )  70.22^(# ) 50.73^(# )  38.64^(# )  Trimethylbenzothiophene benzo(b)thiopheneDibenzothiophene dibenzothiophene 0.04* 0.02* 0.01* 0.01* 0.00* oxide5-oxide Dibenzothiophene dibenzothiophene  5.39 ^(C)  3.57 ^(C)  2.53^(C)  1.89 ^(C)  1.47 ^(C) sulfone 5,5-dioxide Dibenzothiophenedibenzothiophene 91.86^(# )  57.34^(# )  39.09^(# )  28.41^(# ) 21.74^(# )  4-Methyldibenzothiophene 4-methyldibenzothiophene 0.07*0.04* 0.02* 0.01* 0.01* oxide 5-oxide 4-Methyldibenzothiophene4-methyldibenzothiophene  8.94 ^(C)  5.76 ^(C)  3.99 ^(C)  2.91 ^(C) 2.23 ^(C) sulfone 5,5-dioxide 4-Methyldibenzothiophene4-methyldibenzothiophene 152.30^(# )  92.43^(# )  61.59^(# ) 43.93^(# )  33.10^(# )  3,6- 3,6- 0.07* 0.03* 0.02* 0.01* 0.01*Dimethyldibenzothiophene dimethyldibenzothiophene oxide 5-oxide 3,6-3,6- 10.82 ^(C )  6.70 ^(C)  4.49 ^(C)  3.18 ^(C)  2.38 ^(C)Dimethyldibenzothiophene dimethyldibenzothiophene sulfone 5,5-dioxide3,6- 3,6- 266.77^(# )  156.42^(# )  101.35^(# )  70.62^(# )  52.19^(# ) Dimethyldibenzothiophene dimethyldibenzothiophene 4,6- 4,6- 0.09* 0.04*0.02* 0.01* 0.01* Dimethyldibenzothiophene dimethyldibenzothiopheneoxide 5-oxide 4,6- 4,6- 11.93 ^(C )  7.40 ^(C)  4.96 ^(C)  3.52 ^(C) 2.64 ^(C) Dimethyldibenzothiophene dimethyldibenzothiophene sulfone5,5-dioxide 4,6- 4,6- 260.12^(# )  152.57^(# )  98.89^(# )  68.92^(# ) 50.95^(# )  Dimethyldibenzothiophene dimethyldibenzothiophene 2,4- 2,4-0.16* 0.08* 0.04* 0.02* 0.01* Dimethyldibenzothiophenedimethyldibenzothiophene oxide 5-oxide 2,4- 2,4- 12.36 ^(C )  7.74 ^(C) 5.24 ^(C)  3.74 ^(C)  2.82 ^(C) Dimethyldibenzothiophenedimethyldibenzothiophene sulfone 5,5-dioxide 2,4- 2,4- 256.02^(# ) 151.26^(# )  98.62^(# )  69.07^(# )  51.28^(# ) Dimethyldibenzothiophene dimethyldibenzothiophene 2,4,7- 2,4,7- 0.10*0.04* 0.02* 0.01* 0.01* Trimethyldibenzothiophenetrimethyldibenzothiophene oxide 5-oxide 2,4,7- 2,4,7- 14.18 ^(C )  8.44^(C)  5.46 ^(C)  3.76 ^(C)  2.74 ^(C) Trimethyldibenzothiophenetrimethyldibenzothiophene sulfone 5,5-dioxide 2,4,7- 2,4,7- 479.76^(# ) 271.64^(# )  171.09^(# )  116.42^(# )  84.38^(# ) Trimethyldibenzothiophene trimethyldibenzothiophene4-Ethyldibenzothiophene 4-ethyldibenzothiophene 0.10* 0.05* 0.02* 0.01*0.01* oxide 5-oxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene15.68 ^(C )  9.84 ^(C)  6.67 ^(C)  4.80 ^(C)  3.63 ^(C) sulfone5,5-dioxide 4-Ethyldibenzothiophene 4-ethyldibenzothiophene 265.19^(# ) 156.66^(# )  102.14^(# )  71.54^(# )  53.11^(# ) 4-Propyldibenzothiophene 4-propyldibenzothiophene 0.13* 0.06* 0.03*0.01* 0.01* oxide 5-oxide 4-Propyldibenzothiophene4-propyldibenzothiophene 24.95^(# )  15.12 ^(C )  9.98 ^(C)  7.01 ^(C) 5.20 ^(C) sulfone 5,5-dioxide 4-Propyldibenzothiophene4-propyldibenzothiophene 457.22^(# )  260.88^(# )  165.37^(# ) 113.16^(# )  82.40^(# )  2-Butyldibenzothiophene 2-butyldibenzothiophene0.17* 0.07* 0.03* 0.02* 0.01* oxide 5-oxide 2-Butyldibenzothiophene2-butyldibenzothiophene 24.48^(# )  14.06 ^(C )  8.85 ^(C)  5.95 ^(C) 4.26 ^(C) sulfone 5,5-dioxide 2-Butyldibenzothiophene2-butyldibenzothiophene 870.44^(# )  473.86^(# )  289.12^(# ) 191.64^(# )  135.89^(# )  2-Pentyldibenzothiophene2-pentyldibenzothiophene 0.34* 0.14* 0.06* 0.03* 0.02* oxide 5-oxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 41.54^(# ) 23.05^(# )  14.11 ^(C )  9.27 ^(C)  6.50 ^(C) sulfone 5,5-dioxide2-Pentyldibenzothiophene 2-pentyldibenzothiophene 1626.19^(#  )  854.93^(# )  507.09^(# )  328.32^(# )  228.33^(# ) 1-Phenyldibenzothiophene 1-phenyldibenzothiophene 0.13* 0.05* 0.02*0.01* 0.01* oxide 5-oxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 20.37^(# )  11.79 ^(C )  7.49 ^(C)  5.09 ^(C) 3.68 ^(C) sulfone 5,5-dioxide 1-Phenyldibenzothiophene1-phenyldibenzothiophene 468.53^(# )  255.95^(# )  156.80^(# ) 104.39^(# )  74.32^(# )  4-Phenyldibenzothiophene4-phenyldibenzothiophene 0.74* 0.33* 0.16* 0.09* 0.05* oxide 5-oxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 20.59^(# )  11.91^(C )  7.56 ^(C)  5.14 ^(C)  3.72 ^(C) sulfone 5,5-dioxide4-Phenyldibenzothiophene 4-phenyldibenzothiophene 441.88^(# ) 239.11^(# )  145.36^(# )  96.15^(# )  68.09^(# )  Dodecane Dodecane4.72E+04 2.75E+04 1.77E+04 1.23E+04 9012.40   Naphthalenebicyclo[4.4.0]deca- 55.90  38.30  28.10  21.80  17.50  1,3,5,7,9-penteneDibutyl sulfoxide 1-butylsulfinyl-butane 0.01* 0.00* 0.00* 0.00* 0.00*Dibutyl sulfone 1-butylsulfonyl-butane  0.50 ^(C)  0.32 ^(C)  0.20 ^(C) 0.13 ^(C)  0.09 ^(C) Dibutyl sulfide 1-butylsulfanyl-butane203.00^(# )  128.00^(# )  87.40^(# )  63.40^(# )  48.10^(# )  Thiophenesulfide tetrahydrothiophene 0.02  0.01  0.01  0.00  0.00  1-oxideThiophene sulfone tetrahydrothiophene 1.50  1.20  1.00  0.90  0.80 1,1-dioxide Thiophene Thiophene 9.80  7.40  5.90  4.80  4.10  TolueneMethylbenzene 42.90  31.20  24.00  19.30  16.10 

In a further embodiment of the present invention, the solventformulation comprises an aqueous solution of acetonitrile and formicacid. The level of extraction and the specific concentration of theselective solvent formulation depend on factors including, but notlimited to the sulfur speciation of the feed hydrocarbon mixture andwhether the target sulfoxide products or sulfoxidation products to beextracted are non-bulky or bulky. In an extractive simulation, COSMO-RSsoftware was used to simulate γ for selective extraction of oxidizedmodel A fuel by solvent formulations of aqueous formic acid andacetonitrile. Table 7A illustrates the activity coefficient of differentconcentrations of aqueous formic acid/acetonitrile. Based on theactivity coefficient values in Table 7A, a useful aqueous formicacid/acetonitrile selective solvent formulation has a concentration of10 W % formic acid, 10 W % acetonitrile and 80 W % water for extractionof thiophene sulfoxide and sulfone, as shown in FIG. 21. It is alsoapparent from FIG. 22 and the data in Table 7A that a suitableconcentration of 25 W % formic acid, 25 W % acetonitrile and 50 W %water for extraction for extraction of DBT sulfoxide combined with DBTsulfone is effective.

TABLE 7A Compound DBT DBT Thiophene Thiophene nC₁₂ sulfoxide sulfone DBTSulfoxide sulfone Thiophene Toluene Solvent Activity Coefficient Water90 W % 1.79E+07 22.90 580.10 2.11E+04 0.80 16.20 250.60 1435.10Acetonitrile 5 W % Formic acid 5 W % Water 80 W % 1.92E+06 5.30 125.102480.70 0.40 8.20 72.20 369.10 Acetonitrile 10 W % Formic acid 10 W %Water 70 W % 4.13E+05 1.90 43.20 581.30 0.30 5.10 30.80 144.80Acetonitrile 15 W % Formic acid 15 W % Water 60 W % 1.35E+05 0.90 19.90204.70 0.20 3.60 16.60 73.20 Acetonitrile 20 W % Formic acid 20 W %Water 50 W % 5.79E+04 0.50 11.10 93.40 0.20 2.70 10.40 43.50Acetonitrile 25 W % Formic acid 25 W % Water 40 W % 2.98E+04 0.30 7.1050.80 0.10 2.20 7.20 29.00 Acetonitrile 30 W % Formic acid 30 W %

In still another embodiment of the process described herein, the solventformulation comprises an aqueous solution of acetic acid and acetone.The level of extraction and the specific concentration of the selectivesolvent formulation depend on factors including, but not limited to thesulfur speciation of the feed hydrocarbon mixture and whether the targetsulfoxide products or sulfoxidation products to be extracted arenon-bulky or bulky. In an extractive simulation, COSMO-RS software wasused to simulate γ for selective extraction of oxidized model A fuel bysolvent formulations of aqueous acetic acid and acetone. Table 8Aillustrates the activity coefficient of different concentrations ofaqueous acetic acid/acetone. Based on the activity coefficient values inTable 8A, a useful aqueous acetic acid/acetone selective solventformulation has a concentration of 10 W % acetic acid, 10 W % acetoneand 80 W % water for extraction of thiophene sulfoxide and sulfone, asshown in FIG. 23. It is also apparent from FIG. 24 and the data in Table8A that a suitable concentration of 20 W % acetic acid, 20 W % acetoneand 60 W % water for extraction for extraction of DBT sulfoxide combinedwith DBT sulfone is effective.

TABLE 8A Compound DBT DBT Thiophene Thiophene nC₁₂ sulfoxide sulfone DBTSulfoxide sulfone Thiophene Toluene Solvent Activity Coefficient Water90 W % 1.29E+06 12.30 330.70 6889.30 0.80 17.50 145.90 586.00 AceticAcid 5 W % Acetone 5 W % Water 80 W % 5.27E+04 2.90 68.30 586.40 0.5010.00 36.00 112.60 Acetic Acid 10 W % Acetone 10 W % Water 70 W %7299.10 1.30 24.40 123.90 0.40 6.60 14.70 39.40 Acetic Acid 15 W %Acetone 15 W % Water 60 W % 1923.60 0.70 11.80 42.80 0.40 4.80 7.8019.10 Acetic Acid 20 W % Acetone 20 W % Water 50 W % 731.30 0.50 6.9019.70 0.30 3.70 4.90 11.20 Acetic Acid 25 W % Acetone 25 W % Water 40 W% 350.40 0.40 4.50 10.90 0.30 3.10 3.50 7.40 Acetic Acid 30 W % Acetone30 W %

In yet a further embodiment of the process described herein, the solventformulation comprises an aqueous solution of acetonitrile and acetone.The level of extraction and the specific concentration of the selectivesolvent formulation depend on factors including, but not limited to thesulfur speciation of the feed hydrocarbon mixture and whether the targetsulfoxide products or sulfoxidation products to be extracted arenon-bulky or bulky. In an extractive simulation, COSMO-RS software wasused to simulate γ for selective extraction of oxidized model A fuel bysolvent formulations of aqueous acetonitrile and acetone. Table 9Aillustrates the activity coefficient of different concentrations ofaqueous acetone/acetonitrile. Based on the activity coefficient valuesin Table 9A and FIGS. 25 and 26, aqueous acetone/acetonitrile selectivesolvent formulations are useful for extraction of sulfoxides, andextraction of sulfones is possible with concentration adjustments.

TABLE 9A Compound DBT DBT Thiophene Thiophene nC₁₂ sulfoxide sulfone DBTSulfoxide sulfone Thiophene Toluene Solvent Activity Coefficient Water90 W % 1.71E+06 16.40 334.60 6452.90 1.00 16.80 139.50 588.60Acetonitrile 5 W % Acetone 5 W % Water 80 W % 6.43E+04 4.10 56.70 456.000.70 8.20 30.80 101.90 Acetonitrile 10 W % Acetone 10 W % Water 70 W %8164.20 1.90 16.90 83.70 0.70 4.60 11.50 32.80 Acetonitrile 15 W %Acetone 15 W % Water 60 W % 1981.00 1.20 7.00 25.90 0.60 3.00 5.80 14.90Acetonitrile 20 W % Acetone 20 W % Water 50 W % 706.30 0.90 3.60 10.900.70 2.10 3.50 8.30 Acetonitrile 25 W % Acetone 25 W % Water 40 W %322.40 0.70 2.10 5.70 0.70 1.60 2.30 5.30 Acetonitrile 30 W % Acetone 30W %

EXAMPLES Example 1

A quantity of 100 mL of a model diesel feed formed of xylene, DBT, DBTsulfoxide and DBT sulfone (with a total sulfur content of 1635 ppmw) wasoxidized by 30 W % aqueous hydrogen peroxide at a temperature of 37° C.and at a pressure of 1 atmosphere for a period of 70 minutes with solidZnO catalyst (1.2 g) and a ratio of oxidant (H₂O₂) to organic sulfur of4:1 in acetic acid, about 10 mL. After the sold catalyst settled, themodel diesel was removed for extraction of sulfoxidation products andremoval of aqueous H₂O₂ using an embodiment of the selective solventformulation of the present invention.

DBT sulfoxide and DBT sulfone were extracted using a selective solventformulation of 50 W % aqueous acetic acid. Two batch extractions weresequentially conducted using a solvent-to-model diesel ratio of about1:1 at a temperature of 23° C. and at a pressure of 1 atmosphere for aperiod of 2 minutes, during which the contents were stirred. Table 10Arepresents the abundance units as determined by gas chromatographicanalysis. The total extraction of DBT sulfoxide and DBT sulfone was 95 W% and 55 W % respectively. Furthermore, the co-extraction of xylene waslimited to 1.9 W % after both extractions, and the co-extraction of DBT(not oxidized) was limited to 13.2 W % after both extractions. The totalsulfur measured by sulfur speciation (using an ANTEK Model 9000 analyzercommercially available from Antek Instruments, Inc., Houston, Tex. USA)determined that the overall sulfur content was reduced by 55 W % asshown at Table 10B.

TABLE 10A Xylene DBT DBT (aromatic) (untreated sulfur) sulfoxide DBTsulfone Model diesel 9283.7 24.44 24.02 25.09 oxidized 1^(st) extraction9155.2 22.09 7.81 19.15 (−1.4%) (−9.6%) (−67.5%) (−23.7%) 2^(nd)extraction 9108.19 21.22 1.26 11.39 (−1.9%) (−13.2%) (−94.8%) (−54.8%)

TABLE 10B Sample ID Total Sulfur, ppm Model diesel reference 1635Oxidize model diesel (reference) 1694 1^(st) extraction 1110 (−32%)2^(nd) extraction  740 (−55%)

Example 2

A quantity of oxidized model diesel feed as used in Example 1 wassubjected to extraction to remove DBT sulfoxide and DBT sulfone using aselective solvent formulation of 70 W % aqueous formic acid. Two batchextractions were sequentially conducted using a solvent to model dieselratio of about 1:1 at a temperature of 23° C. and at a pressure of 1atmosphere for a period of 2 minutes, during which the contents werestirred. Table 11A represents the abundance units as a result of gaschromatography. The total extraction of DBT sulfoxide and DBT sulfonewas 94 W % and 56 W % respectively. Furthermore, the co-extraction ofxylene was limited to 2 W % after the first extraction, and increased by3.8 W % after the second extraction, based on the normalizationpercentage of the peak regions for the GC analysis for each extraction.The normalization method is qualitative and quasi-quantitative, so thatthe peak area varies. The slight positive (3.8%) of xylene is due to thenormalization of the sum of all peaks and it was changed by materialbalance variation and/or with measurement error.

The co-extraction of DBT (not oxidized) was limited to 10 W % after bothextractions. The total sulfur measured by sulfur speciation determinedthat the overall sulfur content was reduced by 56 W % as shown in Table11B.

TABLE 11A Xylene DBT DBT (aromatic) (untreated sulfur) sulfoxide DBTsulfone Model diesel 9283.7 24.44 24.02  25.09 oxidized 1^(st)extraction 9111.6 21.89 6.45 17.46 (−1.9%) (−10.4%) (−73.1%) (−30.4%)2^(nd) extraction 9635.5 22 1.38 11.14 (+3.8%) (−10.0%)   (−94%)(−55.6%)

TABLE 11B Sample ID Total Sulfur, ppm Model diesel reference 1635Oxidize model diesel 1694 (reference) 1^(st) extraction  960 (−41%)2^(nd) extraction  720 (−56%)

Example 3

A quantity of oxidized model diesel feed as used in Example 1 wassubjected to extraction to remove DBT sulfoxide and DBT sulfone using aselective solvent formulation of 50 W % aqueous methanol. One extractionwas conducted using a solvent to model diesel ratio of about 1:1 at atemperature of 23° C. and at a pressure of 1 atmosphere for a period of2 minutes, during which the contents were stirred. Table 12A representsthe abundance units as a result of gas chromatography. The totalextraction of DBT sulfoxide was 51.5 W %. Furthermore, there was noco-extraction of xylene, as the amount of xylene increased by 2.8 W %after extraction (based on the normalized GC results). The co-extractionof DBT (not oxidized) was limited to 3.1 W %. The total sulfur measuredby sulfur speciation determined that the overall sulfur content wasreduced by 16 W % as shown at Table 12B.

TABLE 12A Xylene DBT DBT (aromatic) (untreated sulfur) sulfoxide DBTsulfone Model diesel 9283.7 24.44 24.02 25.09 oxidized 1^(st) extraction9540.4 23.69 11.64 24.49 +2.8%) (−3.1%) (−51.5%) (−2.4%)

TABLE 12B Sample ID Total Sulfur, ppm Model diesel reference 1635Oxidize model diesel 1694 (reference) 1^(st) extraction 1376 (−16%)

Example 4

A quantity of 60 mL of straight run diesel from a refinery thatcontained about 7600 ppm sulfur was oxidized by 10 g 30 W % hydrogenperoxide and 20 g acetic acid at mild temperature (35° C.) for 4 hoursto generate sulfoxide and sulfones of organic sulfur in diesel.

The oxidized diesel was extracted twice at ratio of 1:2 solvent todiesel of each batch extraction. The total sulfur content was measuredby sulfur speciation (using an ANTEK Model 9000 analyzer) afteroxidative desulfurization treatment.

After the first batch extraction using 30 ml 50 W % acetic acid, thetotal sulfur was decreased from 7600 ppm to 5402 ppm (28.9 W %) and thetotal reduction of diesel volume was 3 mL (5 volume % or V %). After thesecond batch extraction using 30 ml 50 W % acetic acid, the total sulfurafter both extractions was decreased to 4875 ppm (36 W %) and the totalreduction of diesel volume after both extractions was 3.5 mL (6 V %).

Example 5

A quantity of 60 mL of straight run diesel from a refinery thatcontained about 7600 ppm sulfur was oxidized by 5 g 30 W % hydrogenperoxide and 20 g acetic acid at mild temperature (35° C.) for 7 hoursto generate sulfoxide and sulfones of organic sulfur in diesel.

The oxidized diesel was extracted twice at ratio of 1:2 solvent todiesel of each batch extraction. The total sulfur content was measuredby sulfur speciation (using an ANTEK Model 9000 analyzer) afteroxidative desulfurization treatment.

After the first batch extraction using 30 ml 50 W % acetic acid, thetotal sulfur was decreased from 7600 ppm to 4957 ppm (34.8 W %) and thetotal reduction of diesel volume was 3 mL (5 V %). After the secondbatch extraction using 30 ml 50 W % acetic acid, the total sulfur afterboth extractions was decreased to 4426 ppm (42 W %) and the totalreduction of diesel volume after both extractions was 3.5 mL (6 V %).

Example 6

A quantity of 60 mL of straight run diesel from a refinery thatcontained about 7600 ppm sulfur was oxidized by 10 g 30 W % hydrogenperoxide and 20 g 85 W % formic acid at mild temperature (35° C.) for 4hours to generate sulfoxide and sulfones of organic sulfur in diesel.

The oxidized diesel was extracted twice at ratio of 1:2 solvent todiesel of each batch extraction. The total sulfur content was measuredby sulfur speciation (using an ANTEK Model 9000 analyzer) afteroxidative desulfurization treatment.

After the first batch extraction using 30 ml 50 W % acetic acid, thetotal sulfur was decreased from 7600 ppm to 4941 ppm (35 W %) and thetotal reduction of diesel volume was 3 mL (5 V %). After the secondbatch extraction using 30 ml 50 W % acetic acid, the total sulfur afterboth extractions was decreased to 4322 ppm (43 W %) and the totalreduction of diesel volume after both extractions was 3.5 mL (6 V %).

Example 7

A quantity of 50 mL of a straight run diesel was tested for the totalacid number using the testing standards set forth under ASTM D664,before and after sulfoxidation treatment. The total acid number of thediesel before oxidation was 0.084 mg KOH/g. The diesel was oxidizedaccording to the procedure described in Example 4. The oxidized sulfurcomponents from the diesel feed were extracted by a 50 W % aqueousacetic acid selective solvent formulation, followed by water polishing.The sulfoxides combined with sulfones were extracted. The total acidnumber of diesel after oxidation and extraction was 0.024 mg KOH/g. Thetests in Example 7 indicate that the acid number is lower afterextraction with the acetic acid formulation followed by water polishingas compared to the original diesel feed.

The method and system of the present invention have been described inthe above description, examples and in the attached drawings; however,modifications will be apparent to those of ordinary skill in the art andthe scope of protection for the invention is to be defined by the claimsthat follow.

We claim:
 1. An oxidative desulfurization process comprising: reactivelysulfoxidating a hydrocarbon fraction containing organosulfur compoundsto produce a hydrocarbon mixture containing product components, andby-product sulfoxides or a combination of sulfoxides and sulfones;contacting the mixture with a selective solvent formulation comprisingan aqueous solution having a concentration of about 2.5 weight % toabout 70 weight % of a polar organic solvent, the polar organic solventselected from the group consisting of acetone, methanol, acetonitrile,acetic acid, formic acid and combinations comprising at least two of theforegoing polar organic solvents, wherein the concentration of theaqueous solution is selected to maximize extraction of targetby-products and minimize co-extraction of product components includingunoxidized organosulfur compounds and hydrocarbons including aromatichydrocarbons, wherein the extraction is conducted at temperatures ofabout 0° C. to about 40° C.; and recovering a hydrocarbon product ofreduced sulfur content.
 2. The process as in claim 1, wherein theconcentration of the aqueous solution is about 2.5 weight % to about 20weight % of acetone, and wherein the target compounds for extraction arenon-bulky sulfoxide products.
 3. The process as in claim 1, wherein theconcentration of the aqueous solution is about 20 weight % to about 50weight % of acetone, and wherein the target compounds for extraction arebulky sulfoxide products.
 4. The process as in claim 1, wherein theconcentration of the aqueous solution is about 10 weight % to about 30weight % of methanol, and wherein the target compounds for extractionare non-bulky sulfoxide products.
 5. The process as in claim 1, whereinthe concentration of the aqueous solution is about 5 weight % to about30 weight % of acetonitrile, and wherein the target compounds forextraction are non-bulky sulfoxide products.
 6. The process as in claim1, wherein the concentration of the aqueous solution is about 20 weight% to about 40 weight % of acetonitrile, and wherein the target compoundsfor extraction are bulky sulfoxide products.
 7. The process as in claim1, wherein the concentration of the aqueous solution is about 2.5 weight% to about 20 weight % of acetic acid, and wherein the target compoundsfor extraction are non-bulky sulfoxide products.
 8. The process as inclaim 1, wherein the concentration of the aqueous solution is about 20weight % to about 40 weight % of acetic acid, and wherein the targetcompounds for extraction are bulky sulfoxide products.
 9. The process asin claim 1, wherein the concentration of the aqueous solution is about 5weight % to about 20 weight % of formic acid, and wherein the targetcompounds for extraction are non-bulky sulfoxide products.
 10. Theprocess as in claim 1, wherein the concentration of the aqueous solutionis ab out 5 weight % to about 30 weight % of acetonitrile and about 5weight % to about 30 weight % of formic acid.
 11. The process as inclaim 1, wherein the concentration of the aqueous solution is about 5weight % to about 30 weight % of acetic acid and about 5 weight % toabout 30 weight % of acetone.
 12. The process as in claim 1, wherein theconcentration of the aqueous solution is about 5 weight % to about 30weight % of acetonitrile and about 5 weight % to about 30 weight % ofacetone.
 13. The process as in claim 1, wherein an activity coefficientof the target by-product is less than about 16.5 and the activitycoefficient of the aromatic hydrocarbons is greater than about 16.5. 14.The process as in claim 1, wherein an activity coefficient of the targetby-product is less than about 16.5 and the activity coefficient ofunoxidized organosulfur compounds is greater than about 16.5.
 15. Amethod of determining an extraction solvent composition for extractingby-products from a hydrocarbon fraction containing by-productscomprising: qualitatively analyzing the hydrocarbon fractions containingby-products to determine the type of by-products, and the type ofaromatic hydrocarbons and/or the type of non-aromatic hydrocarbons;selecting as a target by-products one or more sulfoxides or acombination of one or more sulfoxides and one or more sulfones;determining the activity coefficient γ of a range of extraction solventcompositions for the target by-products and at least one type ofaromatic or non-aromatic hydrocarbon, the extraction solventcompositions within the range of extraction solvent compositionscomprising an aqueous solution having a concentration of about 2.5weight % to about 70 weight % by weight polar organic solvent in water,the polar organic solvent selected from the group consisting of acetone,methanol, acetonitrile, acetic acid, formic acid and combinationscomprising two or more of acetone, methanol, acetonitrile, acetic acidand formic acid; selecting an extraction solvent composition having anactivity coefficient of less than about 16.5 for the target by-productsthat maximizes extraction of the target by-products, and an activitycoefficient greater than about 16.5 for the at least one type ofaromatic or non-aromatic hydrocarbon that minimizes co-extraction of theat least one type of aromatic or non-aromatic hydrocarbon.
 16. Theprocess as in claim 1, wherein the concentration of the aqueous solutionis about 20 weight % to about 60 weight % of methanol, and wherein thetarget compounds for extraction are bulky sulfoxide products.
 17. Theprocess as in claim 1, wherein the concentration of the aqueous solutionis about 20 weight % to about 40 weight % of formic acid, and whereinthe target compounds for extraction include 4,6-dimethyldibenzothiopheneoxide.
 18. The process as in claim 1, wherein the concentration of theaqueous solution is about 20 weight % to about 30 weight % of acetone,and wherein the target compounds for extraction are non-bulky sulfoxidesand sulfones.
 19. The process as in claim 1, wherein the concentrationof the aqueous solution is about 30 weight % to about 50 weight % ofmethanol, and wherein the target compounds for extraction includedibutyl sulfoxides, dibutyl sulfone, thiophene sulfide, and thiophenesulfone.
 20. The process as in claim 1, wherein the concentration of theaqueous solution is about 10 weight % to about 20 weight % ofacetonitrile, and wherein the target compounds for extraction includethiophene sulfide and thiophene sulfone.
 21. The process as in claim 1,wherein the concentration of the aqueous solution is about 10 weight %to about 30 weight % of acetic acid, and wherein the target compoundsfor extraction include thiophene sulfide and thiophene sulfone.
 22. Theprocess as in claim 1, wherein the concentration of the aqueous solutionis about 30 weight % to about 40 weight % of formic acid, and whereinthe target compounds for extraction include thiophene sulfide andthiophene sulfone.
 23. The process as in claim 1, wherein reactivelysulfoxidating a hydrocarbon fraction is effected by an oxidation processselected from the group consisting of photooxidation, photochemicaloxidation, ozonation, ionic liquid oxidation, electro chemicaloxidation, bio-desulfurization, oxidation by hydrogen peroxide,oxidation by organic peracid, oxidation by peroxomonophosphoric acid,oxidation by nitrogen oxides, oxidation by nitric acid, and acombination of any of the foregoing oxidation processes.